What’s Vulnerable › Vulnerabilities

CVE-2026-3256: HTTP::Session versions before 0.54 for Perl defaults to using insecurely generated session ids

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-28 · updated 2026-06-29
• Weakness: CWE-338

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

• KTAT Http::Session: through 0.53

References

• https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/MD5.pm
• https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/SHA1.pm
• https://metacpan.org/release/TOKUHIROM/http-session-0.54/changes
• https://security.metacpan.org/docs/guides/random-data-for-security.html
• http://www.openwall.com/lists/oss-security/2026/03/28/5

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