CVE-2026-56016

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreHIGH confidence

Score 5.9 from GitHub Security Advisory published 2026-07-01. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 sources updated this week
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.9Exploit: NoneExposed: 0

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

CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources.

The generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible.

An attacker who predicts a session id can impersonate the corresponding session and bypass authentication.

CVSS v3
5.9
EG Score
5.9(high)
EPSS
24.1%
KEV
Not listed

Published

July 1, 2026

Last Modified

July 2, 2026

Advisory Details (3)

Auto-updated Jul 5, 2026
No patch confirmed yet.
generic

oss-security - CVE-2026-56016: CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources

http://www.openwall.com/lists/oss-security/2026/07/01/6
generic

lib/CGI/Session/ID/md5.pm - metacpan.org

https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm
generic

Changes - metacpan.org

https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes

Vendor Advisories for CVE-2026-56016(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 18× in last 7d / 18× 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. 2026-07-07 03:08 UTCEG score recompute
  2. 2026-07-07 03:08 UTCGHSA enrichment
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 04:30 UTCEG score recompute
  6. 2026-07-06 04:30 UTCGHSA enrichment
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-06 02:23 UTCEPSS rescore
  9. 2026-07-05 05:54 UTCEG score recompute
  10. 2026-07-05 05:54 UTCGHSA enrichment
  11. 2026-07-05 02:31 UTCEPSS rescore
  12. 2026-07-05 02:30 UTCEPSS rescore
  13. 2026-07-04 07:17 UTCEG score recompute▲ 5.90
  14. 2026-07-04 07:17 UTCGHSA enrichment
  15. 2026-07-01 17:06 UTCNVD updateCVSS v3 → 5.9 · severity → MEDIUM
  16. 2026-07-01 15:07 UTCEPSS rescore
  17. 2026-07-01 09:23 UTCEG score recompute
  18. 2026-07-01 09:22 UTCNVD updatefirst tracked

Frequently asked(5)

What is CVE-2026-56016?
CVE-2026-56016 is a medium vulnerability published on July 1, 2026. CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources. The generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID…
When was CVE-2026-56016 disclosed?
CVE-2026-56016 was first published in the National Vulnerability Database on July 1, 2026, with the most recent update on July 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56016 actively exploited?
CVE-2026-56016 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 24.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-56016?
CVE-2026-56016 has a CVSS v3.1 base score of 5.9 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-56016?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56016, 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

Explore the affected products and dependency analysis for CVE-2026-56016

Explore →

Is Your Infrastructure Affected by CVE-2026-56016?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs