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

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CVE-2026-42256

Severity CVSS v4.0:
MEDIUM
Type:
Unavailable / Other
Publication date:
09/05/2026
Last modified:
18/05/2026

Description

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

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:*:* 0.4.0 (including) 0.4.24 (excluding)
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* 0.5.0 (including) 0.5.14 (excluding)
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* 0.6.0 (including) 0.6.4 (excluding)

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


References to Advisories, Solutions, and Tools