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Vulnerability record · CVE-2026-42257 · published 9 May 2026

CVE-2026-42257: Ruby-lang net\ command injection vulnerability

Ruby Lang · Net\

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 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.

5.8 CVSS 4.0 Medium EPSS 0.52% · top 58.2% CWE-77 · Command injectionCWE-93 · CWE-93
5.8CVSS 4.0 base score
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
24 Jul 2026Last modified by NVD

Description

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 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.

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/ruby/net-imap/releases/tag/v0.4.24 Release Notes
https://github.com/ruby/net-imap/releases/tag/v0.5.14 Release Notes
https://github.com/ruby/net-imap/releases/tag/v0.6.4 Release Notes
https://github.com/ruby/net-imap/security/advisories/GHSA-hm49-wcqc-g2xg MitigationVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-42257), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.