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CVE-2026-42257

39
FAUCET Score

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.

First published: May 9, 2026Last modified: May 9, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 0.4.24CPE matchmatch criteria
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*
>= 0.5.0, < 0.5.14CPE matchmatch criteria
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*
>= 0.6.0, < 0.6.4CPE matchmatch criteria
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*

CVSS Data

CVSS version used by this source: 4.0

5.8MEDIUM

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:X/V:X/RE:X/U:X

Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
PASSIVE
VS Confidentiality
NONE
VS Integrity
HIGH
VS Availability
LOW
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.43%
Probability of exploitation in next 30 days
EPSS Percentile
35.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0043 is in the 12th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (6)

rubygemspatch availablevia ghsa
Product: net-imapFixed in: 0.6.4
rubygemspatch availablevia ghsa
Product: net-imapFixed in: 0.5.14
rubygemspatch availablevia ghsa
Product: net-imapFixed in: 0.4.24
ubuntupatch availablevia ubuntu_usn
Product: ruby2.5 (bionic)Fixed in: 2.5.1-1ubuntu1.16+esm8
ubuntupatch availablevia ubuntu_usn
Product: ruby2.3 (xenial)Fixed in: 2.3.1-2~ubuntu16.04.16+esm14
github_advisoryworkaround availablevia nvd_reference
View patch

Vendor Advisories (3)

ubuntuUSN-8431-1

Ruby vulnerabilities

Jun 15, 2026
microsoft2026-May/CVE-2026-42257Moderate

net-imap: Command Injection via "raw" arguments to multiple commands

May 7, 2026
rubygemsGHSA-hm49-wcqc-g2xgmedium

net-imap vulnerable to command Injection via "raw" arguments to multiple commands

May 4, 2026

References

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