CVE-2026-42258

Name: CVE-2026-42258
Creator: NVD / NIST
Published: 2026-05-09T20:16:28.623+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.8/10EPSS 0.94%

Last modified Jun 26, 2026

CVE-2026-42258 is a medium-severity vulnerability rated 5.8/10 on the CVSS scale. 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, symbol arguments to commands are vulnerable to a CRLF Injection / IMAP Command injection via Symbol arguments passed to IMAP commands. EPSS estimates a 0.94% chance of exploitation in the next 30 days.

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, symbol arguments to commands are vulnerable to a CRLF Injection / IMAP Command injection via Symbol arguments passed to IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L

CVSS 4.0

5.8/10

CVSS:4.0/AV:L/AC:H/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:X/V:X/RE:X/U:X

EPSS Probability

0.94%

56.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Ruby-Lang	Net\	< 0.4.24	Imap
Ruby-Lang	Net\	>= 0.5.0, < 0.5.14	Imap
Ruby-Lang	Net\	>= 0.6.0, < 0.6.4	Imap

References

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-75xq-5h9v-w6pxMitigation, Vendor Advisory

Timeline

Published: May 9, 2026
Last Modified: Jun 26, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-42258?

How severe is CVE-2026-42258?

CVE-2026-42258 has a CVSS score of 5.8/10 (MEDIUM severity). The EPSS model estimates a 0.94% probability of exploitation in the next 30 days.

How do I fix CVE-2026-42258?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-42258?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST