CVE-2026-3256

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-03-28. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, ghsa
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
9.8
EG Score
9.8(medium)
EPSS
41.0%
KEV
Not listed

Published

March 28, 2026

Last Modified

June 29, 2026

Advisory Details (5)

Auto-updated Jun 29, 2026
No patch confirmed yet.
generic

oss-security - CVE-2026-3256: HTTP::Session versions through 0.53 for Perl defaults to using insecurely generated session ids

http://www.openwall.com/lists/oss-security/2026/03/28/5
generic

CPAN Author’s Guide to Random Data for Security — CPAN Security Group (CPANSec) 🦆

https://security.metacpan.org/docs/guides/random-data-for-security.html
generic

Changes - metacpan.org

https://metacpan.org/release/TOKUHIROM/http-session-0.54/changes
generic

lib/HTTP/Session/ID/SHA1.pm - metacpan.org

https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/SHA1.pm
generic

lib/HTTP/Session/ID/MD5.pm - metacpan.org

https://metacpan.org/release/KTAT/http-session-0.53/source/lib/HTTP/Session/ID/MD5.pm

Vendor Advisories for CVE-2026-3256(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 15× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-09 19:10 UTCEPSS rescore
  3. 2026-07-08 15:15 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 16:27 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 06:31 UTCEPSS rescore
  10. 2026-07-01 15:06 UTCEPSS rescore
  11. 2026-06-30 23:22 UTCEPSS rescore
  12. 2026-06-29 14:06 UTCEPSS rescore
  13. 2026-06-29 07:02 UTCEG score recompute
  14. 2026-06-29 07:02 UTCGHSA enrichment
  15. 2026-06-29 07:02 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-3256?
CVE-2026-3256 is a critical vulnerability published on March 28, 2026. 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…
When was CVE-2026-3256 disclosed?
CVE-2026-3256 was first published in the National Vulnerability Database on March 28, 2026, with the most recent update on June 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-3256 actively exploited?
CVE-2026-3256 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 41.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-3256?
CVE-2026-3256 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-3256?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-3256, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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