CVE Explorer
CVE-2026-13221
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 (
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"collectionURL":"https://cpan.org/modules","defaultStatus":"unaffected","packageName":"perl","product":"perl","programFiles":["regcomp_study.c"],"programRoutines":[{"name":"Perl_study_chunk"}],"repo":"https://github.com/Perl/perl5","vendor":"SHAY","versions":[{"lessThanOrEqual":"5.43.9","status":"affected","version":"0","versionType":"custom"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:8d55aa26410193c227f8f37ed162e972b209a1c0aff72c7f1ae083828a150801 · sha256:99dcf4d454af9700… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":9.1,"baseSeverity":"CRITICAL","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:8d55aa26410193c227f8f37ed162e972b209a1c0aff72c7f1ae083828a150801 · sha256:99dcf4d454af9700… · /containers/adp/1/metrics/0/cvssV3_1
CWE assertions
1 source assertion{"cweId":"CWE-190","description":"CWE-190 Integer Overflow or Wraparound","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:8d55aa26410193c227f8f37ed162e972b209a1c0aff72c7f1ae083828a150801 · sha256:99dcf4d454af9700… · /containers/cna/problemTypes/0/descriptions/0
Source references
3 source assertions{"url":"http://www.openwall.com/lists/oss-security/2026/07/13/5"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:8d55aa26410193c227f8f37ed162e972b209a1c0aff72c7f1ae083828a150801 · sha256:99dcf4d454af9700… · /containers/adp/0/references/0
{"tags":["patch"],"url":"https://github.com/Perl/perl5/commit/03f74bbbd3a68350d926ee93d56ee4808c28c4c7.patch"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:8d55aa26410193c227f8f37ed162e972b209a1c0aff72c7f1ae083828a150801 · sha256:99dcf4d454af9700… · /containers/cna/references/0
{"tags":["issue-tracking"],"url":"https://github.com/Perl/perl5/issues/23388"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:8d55aa26410193c227f8f37ed162e972b209a1c0aff72c7f1ae083828a150801 · sha256:99dcf4d454af9700… · /containers/cna/references/1
Attribution and limitations
- CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →
Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.