{"id":"UBUNTU-CVE-2026-13221","details":"Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.10 produce silently incorrect regular expression matches when an alternation of more than 65535 fixed string branches is compiled into a trie in Perl_study_chunk. When such branches are combined into a trie, the delta between the first branch and the shared tail is stored in a 16-bit field. A branch count above 65535 overflows the field, and the trie's match decision table is truncated with no warning or error. A pattern of this shape produces false positive matches (matching strings it should not) and false negative matches (failing to match strings it should). When such a pattern gates an access or filtering decision, the result is wrong.","modified":"2026-09-16T14:01:35.942495129Z","published":"2026-07-13T17:16:00Z","related":["USN-8675-1","USN-8675-2","USN-8684-1"],"upstream":["CVE-2026-13221"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-13221"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-13221"},{"type":"REPORT","url":"https://lists.security.metacpan.org/cve-announce/msg/41780104/"},{"type":"REPORT","url":"https://github.com/Perl/perl5/issues/23388"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8675-1"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8684-1"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8675-2"}],"affected":[{"package":{"name":"perl","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/perl?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.18.2-2ubuntu1.7+esm8"}]}],"versions":["5.14.2-21build1","5.18.1-4","5.18.1-4build1","5.18.1-5","5.18.2-2","5.18.2-2ubuntu1","5.18.2-2ubuntu1.1","5.18.2-2ubuntu1.3","5.18.2-2ubuntu1.4","5.18.2-2ubuntu1.6","5.18.2-2ubuntu1.7","5.18.2-2ubuntu1.7+esm3","5.18.2-2ubuntu1.7+esm4","5.18.2-2ubuntu1.7+esm5","5.18.2-2ubuntu1.7+esm7"],"ecosystem_specific":{"availability":"Available 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with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13221.json"}},{"package":{"name":"perl","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/perl?arch=source&distro=esm-infra%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.26.1-6ubuntu0.7+esm3"}]}],"versions":["5.26.0-8ubuntu1","5.26.1-2ubuntu1","5.26.1-3","5.26.1-4","5.26.1-4build1","5.26.1-5","5.26.1-6","5.26.1-6ubuntu0.1","5.26.1-6ubuntu0.2","5.26.1-6ubuntu0.3","5.26.1-6ubuntu0.5","5.26.1-6ubuntu0.6","5.26.1-6ubuntu0.7","5.26.1-6ubuntu0.7+esm2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro","binaries":[{"binary_name":"libperl5.26","binary_version":"5.26.1-6ubuntu0.7+esm3"},{"binary_name":"perl","binary_version":"5.26.1-6ubuntu0.7+esm3"},{"binary_version":"5.26.1-6ubuntu0.7+esm3","binary_name":"perl-base"},{"binary_name":"perl-debug","binary_version":"5.26.1-6ubuntu0.7+esm3"},{"binary_name":"perl-modules-5.26","binary_version":"5.26.1-6ubuntu0.7+esm3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13221.json"}},{"package":{"name":"perl","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/perl?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.30.0-9ubuntu0.5+esm3"}]}],"versions":["5.28.1-6build1","5.30.0-7","5.30.0-9","5.30.0-9build1","5.30.0-9ubuntu0.2","5.30.0-9ubuntu0.3","5.30.0-9ubuntu0.4","5.30.0-9ubuntu0.5","5.30.0-9ubuntu0.5+esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"5.30.0-9ubuntu0.5+esm3","binary_name":"libperl5.30"},{"binary_name":"perl","binary_version":"5.30.0-9ubuntu0.5+esm3"},{"binary_version":"5.30.0-9ubuntu0.5+esm3","binary_name":"perl-base"},{"binary_version":"5.30.0-9ubuntu0.5+esm3","binary_name":"perl-debug"},{"binary_name":"perl-modules-5.30","binary_version":"5.30.0-9ubuntu0.5+esm3"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13221.json"}},{"package":{"name":"perl","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/perl?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.34.0-3ubuntu1.8"}]}],"versions":["5.32.1-3ubuntu3","5.34.0-3ubuntu1","5.34.0-3ubuntu1.1","5.34.0-3ubuntu1.2","5.34.0-3ubuntu1.3","5.34.0-3ubuntu1.4","5.34.0-3ubuntu1.5","5.34.0-3ubuntu1.7"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"libperl5.34","binary_version":"5.34.0-3ubuntu1.8"},{"binary_name":"perl","binary_version":"5.34.0-3ubuntu1.8"},{"binary_version":"5.34.0-3ubuntu1.8","binary_name":"perl-base"},{"binary_name":"perl-debug","binary_version":"5.34.0-3ubuntu1.8"},{"binary_name":"perl-modules-5.34","binary_version":"5.34.0-3ubuntu1.8"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13221.json"}},{"package":{"name":"perl","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/perl?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.38.2-3.2ubuntu0.4"}]}],"versions":["5.36.0-9ubuntu1","5.36.0-10ubuntu1","5.38.2-3","5.38.2-3.2","5.38.2-3.2build1","5.38.2-3.2build2","5.38.2-3.2build2.1","5.38.2-3.2ubuntu0.1","5.38.2-3.2ubuntu0.2","5.38.2-3.2ubuntu0.3"],"ecosystem_specific":{"binaries":[{"binary_name":"libperl5.38t64","binary_version":"5.38.2-3.2ubuntu0.4"},{"binary_version":"5.38.2-3.2ubuntu0.4","binary_name":"perl"},{"binary_name":"perl-base","binary_version":"5.38.2-3.2ubuntu0.4"},{"binary_version":"5.38.2-3.2ubuntu0.4","binary_name":"perl-debug"},{"binary_name":"perl-modules-5.38","binary_version":"5.38.2-3.2ubuntu0.4"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13221.json"}},{"package":{"name":"perl","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/perl?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.40.1-7ubuntu0.3"}]}],"versions":["5.40.1-6build1","5.40.1-7build1","5.40.1-7ubuntu0.1","5.40.1-7ubuntu0.2"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"libperl5.40","binary_version":"5.40.1-7ubuntu0.3"},{"binary_name":"perl","binary_version":"5.40.1-7ubuntu0.3"},{"binary_version":"5.40.1-7ubuntu0.3","binary_name":"perl-base"},{"binary_version":"5.40.1-7ubuntu0.3","binary_name":"perl-debug"},{"binary_version":"5.40.1-7ubuntu0.3","binary_name":"perl-modules-5.40"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-13221.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}