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.
Analysis
Analysis and contextual insights are available on OpenCVE Cloud.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| SHAY | perl | unaffected |
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| Vendor | Product | Confidence | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Shay | Perl | 100% |
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Vendor Solution
Apply the upstream patch. The fix is included in the Perl 5.43.10 development release.
Tracking
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Mon, 13 Jul 2026 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Shay
Shay perl |
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| Vendors & Products |
Shay
Shay perl |
Mon, 13 Jul 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | 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 | |
| Weaknesses | CWE-190 | |
| References |
|
MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-07-13T19:30:45.640Z
Reserved: 2026-06-24T15:38:41.010Z
Link: CVE-2026-13221
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-07-13T18:00:04Z