Review reviewCritical

CVE-2026-3256

KTAT HTTP::Session, http::session

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.

CVSS: 9.8
EPSS: 0.53%
CISA KEV: Not listed
Published: 2026.03.29

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.53%

Technical severityCVSS 9.8

Vulnerability overview

Affected product and versions

Product: KTAT HTTP::Session, http::session
Affected versions: <= 0.53
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that KTAT HTTP::Session, http::session and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-338, CWE-340