USN-8675-2: Perl vulnerabilities
Ubuntu issued USN-8675-2 fixing two Perl flaws (CVE-2026-12087, CVE-2026-13221) enabling information disclosure and regex-based security bypass on 26.04 LTS.
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CVE-2026-13221
- CVSS 3.1
- 9.1 critical
- EPSS
- <1%p36
- Published
- ·
- Modified
Description · NVD
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.