CVE-2026-13221
Description
Perl versions through 5.43.9 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.
Metadata
Severity & Metrics
No CVSS data available.
Affected products (1)
| Vendor | Product | Platform | Versions |
|---|---|---|---|
| SHAY | perl | — | 0 ≤ 5.43.9 |
Weakness (CWE)
| CWE | Source | Description |
|---|---|---|
| CWE-190 | cna | CWE-190 Integer Overflow or Wraparound |
References (2)