Home/CVE/Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5
CVE

CVE-2026-42257

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled input, it may contain CRLF sequences, which an attacker can use to inject arbitrary IMAP commands.

This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

CRITICAL · CVSS 9.8 EPSS 0.00016
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
▤

Affected Products & Versions

3
ruby-lang net\< 0.4.24
ruby-lang net\>= 0.5.0 and < 0.5.14
ruby-lang net\>= 0.6.0 and < 0.6.4
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
RubyGems net-imap MODERATE fixed in 0.6.4
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD09 May 2026 · 08:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

1
msrcCVE-2026-42257
🔗

References & Sources

4
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/ruby/net-imap/releases/tag/v0.4.24Release Notes
https://github.com/ruby/net-imap/releases/tag/v0.5.14Release Notes
https://github.com/ruby/net-imap/releases/tag/v0.6.4Release Notes
https://github.com/ruby/net-imap/security/advisories/GHSA-hm49-wcqc-g2xgMitigationVendor Advisory
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