CVE-2026-3255

HTTP::Session2 versions before 1.12 for Perl for Perl may generate weak session ids using the rand() function. The HTTP::Session2 session id generator returns a SHA-1 hash seeded with the built-in rand function, the 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. HTTP::Session2 after version 1.02 will attempt to use the /dev/urandom device to generate a session id, but if the device is unavailable (for example, under Windows), then it will revert to the insecure method described above.

Score

CVSS 3.1 6.5 Medium

Status

Analyzed - 9b29abf9-4ab0-4765-b253-1875cd9b441e

Published

2026-02-27

Last modified

2026-03-03

Weaknesses

CWE-338, CWE-340

Affected products

• Http\ (Tokuhirom)
• Httpsession2 (Tokuhirom)

References

• https://github.com/tokuhirom/HTTP-Session2/commit/9cfde4d7e0965172aef5dcfa3b03bb48df93e636.patch
• https://metacpan.org/release/TOKUHIROM/HTTP-Session2-1.01/source/lib/HTTP/Session2/ServerStore.pm#L68
• https://metacpan.org/release/TOKUHIROM/HTTP-Session2-1.11/source/lib/HTTP/Session2/Random.pm#L35
• https://metacpan.org/release/TOKUHIROM/HTTP-Session2-1.12/changes
• http://www.openwall.com/lists/oss-security/2026/02/27/12