Vulnerability · Published Mar 28, 2026 · Assigned by CPANSec
CVE-2026-3256HTTP::Session versions before 0.54 for Perl defaults to using insecurely generated session ids
Critical 9.8
In plain English
A critical-severity security flaw in HTTP::Session from KTAT. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities).
Official description
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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| KTAT | HTTP::Session | 0 – before 0.54 |
Weakness: CWE-340, CWE-338 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References
- https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/SHA1.pm
- https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/MD5.pm
- https://security.metacpan.org/docs/guides/random-data-for-security.html technical-description
- https://metacpan.org/release/TOKUHIROM/http-session-0.54/changes release-notes
- http://www.openwall.com/lists/oss-security/2026/03/28/5