{"id":"DEBIAN-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":"2026-09-12T10:00:06.459662445Z","published":"2026-07-13T17:16:48.923Z","upstream":["CVE-2026-13221"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-13221"}],"affected":[{"package":{"name":"perl","ecosystem":"Debian:12","purl":"pkg:deb/debian/perl?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.36.0-10","5.36.0-7","5.36.0-7+deb12u1","5.36.0-7+deb12u2","5.36.0-7+deb12u3","5.36.0-8","5.36.0-9","5.38.0-1","5.38.0-2","5.38.0~rc2-1","5.38.2-1","5.38.2-2","5.38.2-3","5.38.2-3.1","5.38.2-3.2","5.38.2-3.2+hurd.1","5.38.2-4","5.38.2-5","5.40.0-1","5.40.0-2","5.40.0-3","5.40.0-4","5.40.0-5","5.40.0-6","5.40.0-7","5.40.0-8","5.40.0~rc1-1","5.40.1-1","5.40.1-2","5.40.1-3","5.40.1-4","5.40.1-5","5.40.1-6","5.40.1-7","5.40.1-8","5.42.0-1","5.42.0-2","5.42.0-3","5.42.2-1","5.42.2-2","5.42.2-3","5.42.3-1","5.44.0-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-13221.json"}},{"package":{"name":"perl","ecosystem":"Debian:13","purl":"pkg:deb/debian/perl?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.40.1-6+deb13u1"}]}],"versions":["5.40.1-6"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-13221.json"}},{"package":{"name":"perl","ecosystem":"Debian:14","purl":"pkg:deb/debian/perl?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.42.3-1"}]}],"versions":["5.40.1-6","5.40.1-7","5.40.1-8","5.42.0-1","5.42.0-2","5.42.0-3","5.42.2-1","5.42.2-2","5.42.2-3"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-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"}]}