Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2025-43857

Severity CVSS v4.0:
MEDIUM
Type:
CWE-400 Uncontrolled Resource Consumption ('Resource Exhaustion')
Publication date:
28/04/2025
Last modified:
21/11/2025

Description

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.5.7, 0.4.20, 0.3.9, and 0.2.5, there is a possibility for denial of service by memory exhaustion when net-imap reads server responses. At any time while the client is connected, a malicious server can send can send a "literal" byte count, which is automatically read by the client's receiver thread. The response reader immediately allocates memory for the number of bytes indicated by the server response. This should not be an issue when securely connecting to trusted IMAP servers that are well-behaved. It can affect insecure connections and buggy, untrusted, or compromised servers (for example, connecting to a user supplied hostname). This issue has been patched in versions 0.5.7, 0.4.20, 0.3.9, and 0.2.5.

Impact

Vector 4.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS v4.0 Severity and Metrics:

Base Score: 6.00 MEDIUM
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): Present
Privileges Required (PR): None
User Interaction (UI): Passsive
Confidentiality (VC): None
Integrity (VI): None
Availability (VA): High
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None

Base Score 4.0
6.00
Severity 4.0
MEDIUM
Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 6.50 MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x
6.50
Severity 3.x
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* 0.2.5 (excluding)
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* 0.3.0 (including) 0.3.9 (excluding)
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* 0.4.0 (including) 0.4.20 (excluding)
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* 0.5.0 (including) 0.5.7 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools