CVE-2026-3256: Ktat Http::session

Critical severity, CVSS 9.8. EPSS: 0.7% chance of exploitation in the next 30 days.

HTTP::Session versions before 0.54 for Perl defaults to using insecurely generated session ids. HTTP::Session defaults to using HTTP::Session::ID::SHA1 to generate session ids using a SHA-1 hash seeded with the built-in rand function, the high resolution epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage. The distribution includes HTTP::session::ID::MD5 which contains a similar flaw, but uses the MD5 hash instead.

Affected products

• Ktat Http::session: up to and including 0.53

Published 2026-03-28. Last modified 2026-06-29.