CVE-2026-3256: Ktat Http::session vulnerability (CVSS 9.8)

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.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Ktat Http::session≤ 0.53

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

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

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-3256 being actively exploited?

CVE-2026-3256 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.71%.

How severe is CVE-2026-3256?

CVE-2026-3256 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.71% probability of exploitation.

Which products are affected by CVE-2026-3256?

Affected products include Ktat Http::session.

How do I fix CVE-2026-3256?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-3256 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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