CVE-2026-13221
Perl regex trie overflow causes incorrect matches, enabling filter/auth bypass.
Is CVE-2026-13221 being exploited?
Not confirmed. CVE-2026-13221 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.43% probability of exploitation in the next 30 days.
How severe is CVE-2026-13221?
CVE-2026-13221 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-13221?
Yes. A fix has been recorded for CVE-2026-13221. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-13221 affect?
CVE-2026-13221 affects Perl <= 5.43.9, Perl-based applications and scripts, CPAN modules using large alternation regexes. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-13221?
Upgrade Perl to a fixed release (>5.43.9) or apply vendor patch immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Overflow in trie makes regex produce false positives/negatives, enabling filter or auth bypass, data leakage, or incorrect access decisions in Perl apps.
Immediate action required