Vulnerability in Ktat HTTP\
CVE-2026-3256
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.007 (51.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 51.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
- Ktat HTTP\ — versions \
- Ktat Http::session — versions 0
- Ktat Http\:\:session
Weakness classification (CWE)
References
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (Product)
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (Product)
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (technical-description, Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (release-notes)
Frequently asked questions
- What is CVE-2026-3256?
- CVE-2026-3256 is a critical-severity vulnerability in Ktat HTTP\, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 9.8/10. Published 2026-03-28.
- How severe is CVE-2026-3256?
- Critical severity. CVSS v3 base score is 9.8 out of 10.