Vulnerabilities

Allocation of resources without limits in the JSON reader of Progressive Robot hMailServer 6.3.2 through 6.3.7 allows a remote attacker to exhaust the server's memory and hold its threads, making mail delivery, the REST API and the webmail unavailable. The reader built a tree of values far larger than the text it read, copying each value into every level above it, and set no bound on the number of values, so a single JSON document of many small values, within the 16 MB the server reads, raised the service's memory by about 2 GB and held one thread for seconds to minutes. From 6.3.4 a remote unauthenticated attacker reaches the reader by mailing such a document as a TLS-RPT report, up to 16 MB once decompressed, to a hosted domain's report mailbox, where an administrator has set one; it is read on a mail delivery thread (ten by default), and those threads deliver all mail, local and outbound. From 6.3.4 it is also reached without an account through the reply to a password-protected message, with the message's link alone, where the REST API is on (it is off by default) and a public base URL for such links is set; and by any account, from 6.3.2 through the webmail's send and draft routes and from 6.3.4 through its other routes granted 16 MB and the send API; the webmail's send, draft and settings routes parsed the body again for each member read. The REST API serves every request on four worker threads, in the process that also serves SMTP, IMAP and POP3, so a few such documents at once make it unavailable and can exhaust the machine's memory and end the whole service. This is a separate defect from CVE-2026-107574, the reader's handling of duplicate member names, fixed in 6.3.6.

The web services listener of Progressive Robot hMailServer 6.3.3 through 6.3.7 does not apply the server's IP ranges to the connections it accepts, which allows a remote unauthenticated attacker to go on guessing account passwords at the listener's sign-ins after the auto-ban has banned the attacker's address. The listener is off by default (WebServicesHttpPort and WebServicesHttpsPort 0). From 6.3.3 its CardDAV, and from 6.3.4 its CalDAV and its Outlook Autodiscover answer to a request that carries credentials, sign an account in with HTTP Basic over HTTPS. A failed sign-in there counts towards the auto-ban as a failed logon on any other protocol does: when the failures counted from one address reach MaxInvalidLogonAttempts (3 within 30 minutes by default), the server writes an IP range that refuses the address for AutoBanMinutes (60 by default), and the SMTP, POP3, IMAP and ManageSieve listeners refuse it. The web services listener asked no IP range when it accepted a connection (in 6.3.3 nothing, from 6.3.4 the country policy alone), so it went on serving such an address, whether its ban had been earned there or on another protocol, and also an address that an administrator's IP range allowing nothing holds. Each failed sign-in there closed only its own connection, and the next connection was accepted, during the ban and after it. The firewall rule and command the auto-ban can drive (AutoBanFirewall and AutoBanCommand, off by default) are told only the SMTP, POP3 and IMAP ports, so that the firewall rule and the packaged hook did not close the listener's ports, and the fail2ban jail packaged for Linux (off by default) lists only the mail and ManageSieve ports. The only limit left on the guesses at one account there was the per-name lockout (AccountLockoutThreshold in hMailServer.ini, 0, off, by default), which has a separate defect fixed in the same release. The flaw is reached on the listener's HTTPS port: behind a TLS-terminating proxy the listener sees the proxy's address for every client, and a ban never named the client there.

The sign-in of Progressive Robot hMailServer 6.2.22-pre2 through 6.3.7 takes for an account names that are not its address but under which the database's own comparison finds it, while the per-name lockout and the compromised-account hold are kept by the name as the client gave it. This allows a remote unauthenticated attacker to go on guessing an account's password beyond the lockout's threshold, and anyone who has the password of an account held for review to sign in to it. The per-name lockout (from 6.2.22-pre2; AccountLockoutThreshold in hMailServer.ini, 0, off, by default) locks a name after repeated failed sign-ins. The hold (from 6.3.4, where the compromised-account detection is set to enforce, which is not the default) refuses an account judged to have been taken over. Both are asked, before the password, of the name the client gave: trimmed, in lower case and with a domain alias or the default domain applied. The account whose password the sign-in then checks is whichever one the database finds under that name. The databases find an account under spellings that this key counts apart. MySQL and MariaDB find it under one with accented letters in place of plain ones, and MariaDB 11.8, in a database made before 6.3.4, also under one with full-width letters, with a single letter in place of a pair of plain ones, or with characters its comparison ignores in any number. SQL Server and SQL Server Compact find it under one with full-width letters or with characters their comparison ignores in any number, and SQL Server also under one with a single letter in place of a pair of plain ones, with a character of Latin-1 in place of a digit and, for an address holding letters of Latin-1 outside ASCII, under those letters in the other case, and, under an accent-insensitive collation, with accented letters. PostgreSQL finds it under one holding a letter whose lower case under the database's locale is a plain letter, and, for an address holding letters outside ASCII, under those letters in the other case; on the build for musl (from 6.3.6) the server's own lower case folds nearly all of these too. On every database, a domain alias saved with white space at the end of its name gives such a spelling too, and on every database but PostgreSQL so does an account's bare local part where the default domain was saved with spaces at its end and no other white space (neither is the default). Each such spelling has a lockout threshold of its own, so the lockout limits the guesses at an account only to its threshold times the number of the account's spellings. That is far beyond any threshold for most addresses on MySQL and MariaDB, and without limit on SQL Server, on SQL Server Compact, the database the Windows installer uses by default, and before 6.3.4 on MariaDB 11.8. A locked name is got round under another spelling. A held account is signed in to under another spelling with its password over IMAP, POP3 and SMTP AUTH, and, where they are turned on (off by default), over ManageSieve, the REST API and the webmail. IMAP LOGIN, offered as installed, carries such spellings on MySQL, MariaDB and SQL Server Compact, and, on SQL Server and PostgreSQL, for some addresses; the sign-ins that carry a name as UTF-8 carry them for the others on SQL Server, and on PostgreSQL for those holding one of the plain letters another letter lowers to or a letter outside ASCII with another case. The same lookup mapped to accounts the names given by an OAuth 2.0 token, a client certificate, a Kerberos ticket and an OpenID Connect or SAML identity provider, where those are set up (none is by default), so that a name an issuer gave to one party could sign in to another's account; OAuth 2.0 tokens were mapped so from 6.2.0, before the per-name lockout existed. A name holding a NUL character, carried from 6.3.0 on Linux and 6.3.3 on Windows, failed the statement on MySQL, MariaDB and PostgreSQL.

The auto-ban of Progressive Robot hMailServer 6.2.0 through 6.3.3, with a MySQL or MariaDB database, can be kept from banning an address after repeated failed logons, which allows a remote unauthenticated attacker to go on guessing account passwords from a single address without being banned. The server makes its MySQL tables in MySQL's utf8 character set, which holds no character outside the Basic Multilingual Plane, sends its statements as UTF-8 over a utf8mb4 connection and leaves the database's default strict mode in place. From 6.2.0 it decodes the user name of a SASL PLAIN logon as UTF-8, so the name can hold such a character. When the failed logons counted from one address reach MaxInvalidLogonAttempts (3 by default), the server clears that address's count, saves an IP range named "Auto-ban: " followed by the user name of the logon that reached the limit, and drops the connection. If such a character is in the part of the user name that the range's name keeps (the name is cut to 100 characters), the database refuses the range: no range is saved, the address is not refused, and, its count having already been cleared, it is given the next full set of attempts. An attacker can in this way spend all but the last attempt of each set on password guesses, and make the last under such a name. On Windows, POP3 AUTH PLAIN reaches it on a server as installed, and IMAP AUTHENTICATE PLAIN where IMAP SASL authentication is turned on (off by default); on Windows and on Linux (from 6.3.0), SMTP AUTH PLAIN reaches it where plain-text authentication is allowed (off by default), and ManageSieve and CardDAV where they are turned on (off by default). Each failed save is reported in the server's error log. A database whose strict mode has been turned off stores the character as a question mark and makes the first such ban, but refuses every later ban named after the same user name, or after one holding other such characters in their place, as a duplicate while the first stands, since the server cannot look up a name holding such a character there.

SQL injection in the database layer of Progressive Robot hMailServer 6.0.0-B1 through 6.2.18, when the server uses MySQL/MariaDB or PostgreSQL, allows a remote attacker to alter SQL statements the server runs. On those two engines parameters are not bound: SQLStatement::GenerateFromCommand wrote each value into the statement's text as a quoted literal with a separate string replacement over the whole text per parameter, so a value holding the name of a parameter substituted after it had that name replaced, inside the value, by the later value with its own quotes, which ended the literal early and placed the later value in the statement as SQL. The row the server writes for each recipient of a queued message carries the recipient's address twice, so in the default configuration an authenticated user who may send mail reaches it by sending to an address of their choosing. A remote unauthenticated sender reaches the same statement through a message the server sends to the envelope sender, such as a delivery failure notice or an automatic reply, and, when greylisting or message indexing is enabled (both are off by default), through the greylisting record's envelope addresses or through the message metadata the server stores for IMAP SORT, which carries four header fields of a received message. An altered statement runs with the privileges of the server's database account; on PostgreSQL, whose client call runs every statement in the text it is given, further statements can follow it, while on MySQL/MariaDB, where one statement is run per call, the change is confined to the statement it is in. SQL Server and SQL Server Compact, where parameters are bound, are not affected.

Progressive Robot hMailServer 6.2.25 through 6.3.7 on Windows, with a PostgreSQL database, the connection's sslmode require, verify-ca or verify-full, and a root certificate file named by PostgreSQLSslRootCert (from 6.2.25) or, with TlsMode=verify-full and neither PostgreSQL key set, by TlsCaFile (from 6.3.4), hands the file's name to libpq as bytes in the system's ANSI code page (up to 6.3.5 as Latin-1 bytes, which on code page 1252 are the code page's own for U+00A0 to U+00FF), and libpq looks for the file by those bytes and then hands the same bytes to OpenSSL, whose file opening on Windows reads a name as UTF-8 first and opens the file at that reading when one is there. When every byte of the name outside ASCII also reads as UTF-8 - for example U+00C3 U+00A9, the bytes C3 A9 on code page 1252, which are U+00E9 in UTF-8 - the database server's certificate was checked against the file at that other name whenever one was there, which allows a local attacker who can create that file but cannot change the configured one, as any user can by default beside a file an administrator keeps under ProgramData, or beside a folder directly under the system drive's root whose permissions the administrator restricted, and who can intercept the connection to the database server or stand in for it, to have hMailServer trust a certificate authority of the attacker's own and read and modify the traffic between hMailServer and its database, the database password included; the file alone, holding no authority that issued the database server's certificate, stops hMailServer from connecting to its database. The same applies in 6.3.4 through 6.3.7 to TlsCaFile when an Oracle MySQL client library has been put in place of the bundled MariaDB Connector/C, since that client opens the file through OpenSSL in the same way; the bundled MariaDB Connector/C opens the file in the code page and is not affected, and neither are the Linux builds. The configuration is not the default: by default no root certificate file is named.

Progressive Robot hMailServer 6.3.4 through 6.3.7, with a MySQL or MariaDB database and TlsMode=verify-full, does not hand the database client the CA file that TlsCaFile names when the file's name contains a character outside ASCII on Linux, or above U+00FF on Windows, which allows an attacker who can intercept the connection to the database server to read and modify the traffic between hMailServer and its database, by presenting, with MariaDB Connector/C 3.4.2 to 3.4.10 as the client, a certificate from any authority, its own included, for any name, and otherwise a certificate for the database server's name issued by any certificate authority in the system's trust store. The server converted the name for the client with the C runtime's conversion in the C locale, which gives an empty string for such a name, and then set no CA file at all, without an error, while certificate verification stayed on, so the client - MariaDB Connector/C, bundled on Windows and the distribution's on Linux - verified the certificate of a database server over the network against the system's trust store instead of the configured CA; Connector/C 3.4.2 to 3.4.10 (bundled on Windows in 6.3.4 to 6.3.6) went further and, with no CA file, took a certificate within its dates whose issuer it could not find, for any name, with neither its chain nor its name checked and no password proof, when the server offered first a sign-in method that hashes the password, which an attacker in the middle chooses (MariaDB's CONC-853, fixed in Connector/C 3.4.11), and Connector/C 3.4 accepted from a MariaDB 11.4 or later server a certificate the store did not vouch for when that server proved it held the account's password; on a connection it treats as local (127.0.0.1, ::1, a Unix socket, a named pipe, and localhost on Windows), Connector/C 3.4.1 and later checked neither the certificate's issuer nor its name, so that a local attacker able to stand in for the database server could present any certificate within its dates of its own making. The settings line of hmailserver --check-database still named the configured file, and the application log said the certificate had been checked. With MariaDB Connector/C 3.4.1 to 3.4.9 as the client - bundled on Windows in 6.3.4 to 6.3.6, and the client of Linux distributions that have not patched it - the missing CA file also met the precondition of CVE-2026-107819, so that a certificate issued for any other name by a trusted authority was enough to obtain the database password. On Linux the file was found only when the server ran on glibc under a locale whose character set holds the name's characters (a UTF-8 locale, or a legacy 8-bit one the system has, in whose bytes the file is then named); with no locale, LC_ALL=C or a locale the system lacks, and on Alpine (musl), the connection failed instead. The configuration is not the default: TlsMode defaults to prefer, which checks no certificate.

Progressive Robot hMailServer 6.3.4 through 6.3.7, with a MySQL or MariaDB database, TlsMode=verify-full and no TlsCaFile, does not verify the database server's certificate's issuer or name when the connection is one that MariaDB Connector/C treats as local - Server= set to 127.0.0.1, ::1 or localhost (on Linux a Unix socket), to . on Windows (a named pipe), or to a comma-separated list of servers that holds such an element - which allows a local attacker who can stand in for the database server, for example by listening on its port while it is stopped or restarting, to receive the database sign-in, the password included, and to read and modify the traffic between hMailServer and its database. hMailServer applied verify-full by turning the client's certificate verification on without a CA file, but MariaDB Connector/C 3.4.1 and later, on a connection they treat as local and with no CA file, accept any certificate within its validity period that is self-signed or sent with its own root, for any name (Connector/C 3.4.2 to 3.4.10 also one whose issuer they cannot find), so the client accepted the certificate an impostor made, asked no proof of the password and allowed a switch to an authentication method that sends the password unhashed, while hmailserver --check-database said the certificate had been checked against the system's trust store and the application log that it had been checked. The Windows builds bundle Connector/C 3.4.9 (6.3.4 to 6.3.6) and 3.4.11 (6.3.7); on Linux the distribution's client is used, and Connector/C 3.3 and 3.4.0 and Oracle's MySQL client are not affected. The configuration is not the default: TlsMode defaults to prefer, which checks no certificate.

Progressive Robot hMailServer 6.2.3 through 6.3.7 on Windows, with a MySQL or MariaDB database, hands the bundled MariaDB Connector/C the folder of its authentication plugins (the plugin folder in the installation's Bin folder) as Latin-1 bytes, which the client reads in the system's ANSI code page when it builds a plugin's path and loads the plugin with LoadLibraryExA, which allows a local authenticated user to execute code as the hMailServer service's account (LocalSystem, or the service's virtual account for a new installation from 6.3.4) by creating the folder those bytes name in the code page and placing in it a DLL with a plugin's name, when the installation folder's path holds a character between U+0080 and U+00FF whose byte the code page reads as another character, and none above U+00FF, and the user can create that other folder (by default any authenticated user may create a folder directly under the root of the system drive). The server converted the path with the C runtime's wcstombs_s in the C locale, which writes each character up to U+00FF as the byte of the same value: on code page 1252 those bytes are the same letters, while on another code page, such as 1251, or on a UTF-8 code page, they name another folder. The client loads the plugin the database server names in its greeting, unless it is built in, and any plugin the server names in an authentication switch, and tries again at each connection while a load fails, so with a MySQL 8.0 or later server, whose greeting names caching_sha2_password by default, the DLL is loaded at the next connection the service makes, whatever plugin the database account uses; a DLL's entry point runs when it is loaded. A path holding any character above U+00FF was handed over as an empty string, whatever the code page, from which the client makes a plugin's name at the root of the current drive: for the service, whose current folder is System32, that is the root of the system drive, where by default only administrators can create a file, but the server's own database commands (hMailServer.exe --check-database, --upgrade-database and the others from 6.3.4, and the /Debug and /Test console modes from 6.2.3) run in the folder they are started from - the product tells administrators to run them from an elevated prompt in the Bin folder, and the setup of 6.3.4 and 6.3.5 ran two or three of them itself with the Bin folder as their working folder for a new installation with an external database - so a DLL that a local authenticated user placed under a plugin's name at the root of a drive other users may write, such as a FAT or exFAT volume, was loaded into the administrator's process at the command's first connection to a MySQL 8.0 or later server. 6.3.8 fixes both cases: it hands the folder in the code page's bytes or by its short (8.3) name, and where neither can be written, a folder under the Windows system folder that holds no plugin and that only administrators can create, or else refuses the connection before attempting it; it never hands the empty value or a folder the current drive completes. The configuration is not the default: the default installation folder, under Program Files, is ASCII. Linux builds set no plugin folder and are not affected.

In affected versions of Octopus Server, incorrect validation of the permissions assigned to a user that would allow them to create project triggers could result in the user being able to run runbooks or create deployments they were not authorised to perform.

The ARforms plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Referer Header in all versions up to, and including, 7.2.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The arf_save_incomplete_form_data() AJAX handler is registered with wp_ajax_nopriv_, meaning unauthenticated attackers can store a malicious payload by submitting a partial form entry with a forged Referer header, with no authentication required at any step.

The ARforms plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'description' parameter in all versions up to, and including, 7.2.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The injected payload is deserialized via maybe_unserialize() when an administrator views the affected entry; if the attacker's array contains a 'referrer' key, the attacker-controlled page_url and http_referrer values are used as-is and rendered unescaped into the admin entry detail view.