Command injection in net-imap - CVE-2026-42257

Vulnerability identifier: #VU162937

CSH Severity: Medium

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-42257

CWE-ID: CWE-77

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows an unprivileged local attacker to execute arbitrary IMAP commands through an application's authenticated connection to a mail server.

The vulnerability exists due to missing validation and escaping of raw arguments in net-imap commands when an application passes unvalidated, user-controlled input to affected methods. An unprivileged local attacker can insert CRLF sequences into these arguments to inject additional commands, such as deleting mailboxes, during normal application use.

net-imap
Debian Linux
Anolis OS
Ubuntu
openEuler
ruby2.3 (Ubuntu package)
libruby2.3 (Ubuntu package)
ruby2.5 (Ubuntu package)
libruby2.5 (Ubuntu package)
rubygem-net-telnet
rubygem-xmlrpc
rubygem-rss
rubygem-abrt
rubygem-abrt-doc
rubygem-io-console
rubygem-mysql2
rubygem-mysql2-doc
rubygem-typeprof
rubygem-power_assert
rubygem-did_you_mean
rubygem-bigdecimal
rubygem-pg
rubygem-pg-doc
rubygem-racc
rubygem-irb
rubygem-json
rubygem-openssl
ruby
ruby-help
ruby-irb
ruby-devel
ruby-debugsource
ruby-debuginfo
rubygem-bundler
rubygems
rubygems-devel
rubygem-psych
rubygem-test-unit
rubygem-rexml
ruby-libs
ruby-default-gems
ruby-doc
ruby-bundled-gems
rubygem-rbs
rubygem-minitest
rubygem-rdoc
rubygem-rake
ruby3.3 (Debian package)

Install security update from vendor's website.

net-imap - addressed in versions 0.4.24, 0.5.14, 0.6.4
ruby2.3 (Ubuntu package) - update to 2.3.1-2~ubuntu16.04.16+esm14
libruby2.3 (Ubuntu package) - update to 2.3.1-2~ubuntu16.04.16+esm14
ruby2.5 (Ubuntu package) - update to 2.5.1-1ubuntu1.16+esm8
libruby2.5 (Ubuntu package) - update to 2.5.1-1ubuntu1.16+esm8
rubygem-net-telnet - update to 0.1.1-138
rubygem-xmlrpc - update to 0.3.0-138
rubygem-rss - update to 0.3.1-8
rubygem-abrt - update to 0.4.0-1
rubygem-abrt-doc - update to 0.4.0-1
rubygem-io-console - update to 0.4.6-138
rubygem-mysql2 - update to 0.5.5-1
rubygem-mysql2-doc - update to 0.5.5-1
rubygem-io-console - update to 0.7.1-8
rubygem-typeprof - update to 0.21.9-8
rubygem-power_assert - update to 1.1.1-138
rubygem-did_you_mean - update to 1.2.0-138
rubygem-bigdecimal - update to 1.3.4-138
rubygem-pg - update to 1.5.4-1
rubygem-pg-doc - update to 1.5.4-1
rubygem-racc - update to 1.7.3-8
rubygem-irb - update to 1.13.1-8
rubygem-power_assert - update to 2.0.3-8
rubygem-json - update to 2.1.0-138
rubygem-openssl - update to 2.1.2-138
ruby - update to 2.5.8-138
ruby-help - update to 2.5.8-138
ruby-irb - update to 2.5.8-138
ruby-devel - update to 2.5.8-138
ruby-debugsource - update to 2.5.8-138
ruby-debuginfo - update to 2.5.8-138
rubygem-bundler - update to 2.5.22-8
rubygem-json - update to 2.7.2-8
rubygems - update to 2.7.6-138
rubygems-devel - update to 2.7.6-138
rubygem-psych - update to 3.0.2-138
rubygem-bigdecimal - update to 3.1.5-8
rubygem-test-unit - update to 3.2.7-138
rubygem-rexml - addressed in versions 3.3.9-8, 3.4.4-8
ruby-libs - addressed in versions 3.3.9-8, 3.3.12-8
ruby-default-gems - addressed in versions 3.3.9-8, 3.3.12-8
ruby-doc - addressed in versions 3.3.9-8, 3.3.12-8
ruby-devel - addressed in versions 3.3.9-8, 3.3.12-8
ruby-bundled-gems - addressed in versions 3.3.9-8, 3.3.12-8
ruby - addressed in versions 3.3.9-8, 3.3.12-8
rubygem-rbs - update to 3.4.0-8
rubygems - update to 3.5.22-8
rubygems-devel - update to 3.5.22-8
rubygem-test-unit - update to 3.6.1-8
rubygem-psych - update to 5.1.2-8
rubygem-minitest - update to 5.10.3-138
rubygem-minitest - update to 5.20.0-8
rubygem-rdoc - update to 6.0.1.1-138
rubygem-rdoc - update to 6.6.3.1-8
rubygem-rake - update to 12.3.0-138
rubygem-rake - update to 13.1.0-8
ruby3.3 (Debian package) - update to 3.3.13-0+deb13u1

• https://github.com/ruby/net-imap/security/advisories/GHSA-hm49-wcqc-g2xg

• Debian update for ruby3.3
• openEuler update for ruby
• Anolis OS update for ruby
• Anolis OS update for ruby:3.3 module
• Multiple vulnerabilities in net-imap
• Ubuntu update for ruby2.3, ruby2.5