Inefficient Algorithmic Complexity in net-imap - CVE-2026-42245

Vulnerability identifier: #VU162939

CSH Severity: Low

CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-42245

CWE-ID: CWE-407

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows an unauthenticated remote attacker to exhaust a net-imap client's CPU and cause a denial of service.

The vulnerability exists due to quadratic processing in Net::IMAP::ResponseReader when repeated scans of a growing response buffer process many string literals. An unauthenticated remote attacker can send crafted responses from a hostile IMAP server to a connected client, causing excessive CPU consumption even below the default max_response_size limit.

net-imap
Debian Linux
Anolis OS
openEuler
Fedora
rubygem-net-telnet
rubygem-xmlrpc
rubygem-rss
rubygem-abrt-doc
rubygem-abrt
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-debugsource
ruby-devel
ruby-debuginfo
ruby-irb
ruby-help
ruby
rubygem-bundler
rubygems-devel
rubygems
rubygem-psych
rubygem-test-unit
ruby-libs
ruby-bundled-gems
ruby-default-gems
ruby-doc
rubygem-rbs
rubygem-rexml
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
rubygem-net-telnet - update to 0.1.1-138
rubygem-xmlrpc - update to 0.3.0-138
rubygem-rss - update to 0.3.1-7
rubygem-abrt-doc - update to 0.4.0-1
rubygem-abrt - 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 0.7.1-7
rubygem-typeprof - update to 0.21.9-7
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 1.7.3-7
rubygem-irb - update to 1.13.1-7
rubygem-power_assert - update to 2.0.3-7
rubygem-json - update to 2.1.0-138
rubygem-openssl - update to 2.1.2-138
ruby-debugsource - update to 2.5.8-138
ruby-devel - update to 2.5.8-138
ruby-debuginfo - update to 2.5.8-138
ruby-irb - update to 2.5.8-138
ruby-help - update to 2.5.8-138
ruby - update to 2.5.8-138
rubygem-bundler - update to 2.5.22-7
rubygem-json - update to 2.7.2-7
rubygems-devel - update to 2.7.6-138
rubygems - update to 2.7.6-138
rubygem-psych - update to 3.0.2-138
rubygem-bigdecimal - update to 3.1.5-7
rubygem-test-unit - update to 3.2.7-138
ruby-devel - update to 3.3.10-7
ruby-libs - update to 3.3.10-7
ruby-bundled-gems - update to 3.3.10-7
ruby - update to 3.3.10-7
ruby-default-gems - update to 3.3.10-7
ruby-doc - update to 3.3.10-7
rubygem-rbs - update to 3.4.0-7
rubygem-rexml - update to 3.4.4-7
ruby - addressed in versions 3.4.10-31.fc43, 4.0.6-36.fc44, 4.0.6-36.fc45
rubygems - update to 3.5.22-7
rubygems-devel - update to 3.5.22-7
rubygem-test-unit - update to 3.6.1-7
rubygem-psych - update to 5.1.2-7
rubygem-minitest - update to 5.10.3-138
rubygem-minitest - update to 5.20.0-7
rubygem-rdoc - update to 6.0.1.1-138
rubygem-rdoc - update to 6.6.3.1-7
rubygem-rake - update to 12.3.0-138
rubygem-rake - update to 13.1.0-7
ruby3.3 (Debian package) - update to 3.3.13-0+deb13u1

• https://github.com/ruby/net-imap/security/advisories/GHSA-q2mw-fvj9-vvcw

• Debian update for ruby3.3
• Fedora 43 update for ruby
• Fedora 45 update for ruby
• Fedora 44 update for ruby
• openEuler update for ruby
• Anolis OS update for ruby:3.3 module
• Multiple vulnerabilities in net-imap