CVE-2026-91939

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-15. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: Elevated riskExposed: 0

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

Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers to instantiate arbitrary PHP classes with attacker-controlled properties. Attackers can exploit PHP object injection through crafted serialized payloads to trigger gadget chains and achieve database manipulation or code execution.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
75(Attend)
EG Risk 75/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
47%
KEV
Not listed

Published

September 15, 2026

Last Modified

September 16, 2026

Advisory Details (7)

Auto-updated Sep 16, 2026
🔬 Proof of concept available. No patch confirmed yet. Sources: github_pr.
generic🟡 PoC Available

Security: PHP object injection via CommentsWidget::run() `ci` parameter · Issue #1888 · Cotonti/Cotonti · GitHub

https://github.com/Cotonti/Cotonti/issues/1888
generic

Cotonti 1.0.0 Comments Plugin PHP Object Injection via ci Parameter | Advisories | VulnCheck

https://www.vulncheck.com/advisories/cotonti-1.0.0-comments-plugin-php-object-injection-via-ci-parameter
github_pr

fix(comments): prevent PHP object injection in CommentsWidget

Upstream fix in progress (PR #1889 · Cotonti/Cotonti, state=open)

https://github.com/Cotonti/Cotonti/pull/1889
generic

Cotonti/plugins/comments/inc/CommentsWidget.php at 1.0.0 · Cotonti/Cotonti · GitHub

https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/inc/CommentsWidget.php
generic

Cotonti/plugins/comments/controllers/actions/DisplayAction.php at 1.0.0 · Cotonti/Cotonti · GitHub

https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/controllers/actions/DisplayAction.php
generic

Cotonti/plugins/comments/comments.setup.php at 1.0.0 · Cotonti/Cotonti · GitHub

https://github.com/Cotonti/Cotonti/blob/1.0.0/plugins/comments/comments.setup.php
generic

GitHub - Cotonti/Cotonti: Fast, reliable and flexible PHP CMF/CMS · GitHub

https://github.com/Cotonti/Cotonti

Vendor Advisories for CVE-2026-91939(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 41× in last 7d / 41× 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. 2026-09-20 13:17 UTCGHSA enrichment
  2. 2026-09-20 09:07 UTCGHSA enrichment
  3. 2026-09-20 04:56 UTCGHSA enrichment
  4. 2026-09-20 00:45 UTCGHSA enrichment
  5. 2026-09-19 20:34 UTCGHSA enrichment
  6. 2026-09-19 16:23 UTCEG score recompute
  7. 2026-09-19 16:23 UTCGHSA enrichment
  8. 2026-09-19 12:12 UTCGHSA enrichment
  9. 2026-09-19 08:02 UTCGHSA enrichment
  10. 2026-09-19 03:51 UTCGHSA enrichment
  11. 2026-09-18 23:41 UTCGHSA enrichment
  12. 2026-09-18 19:31 UTCEG score recompute
  13. 2026-09-18 19:31 UTCGHSA enrichment
  14. 2026-09-18 19:28 UTCEPSS rescore
  15. 2026-09-18 15:16 UTCGHSA enrichment
  16. 2026-09-18 11:06 UTCGHSA enrichment
  17. 2026-09-18 06:56 UTCGHSA enrichment
  18. 2026-09-18 02:45 UTCGHSA enrichment
  19. 2026-09-17 22:35 UTCEG score recompute
  20. 2026-09-17 22:34 UTCGHSA enrichment
  21. 2026-09-17 19:32 UTCEPSS rescore
  22. 2026-09-17 18:23 UTCGHSA enrichment
  23. 2026-09-17 13:46 UTCGHSA enrichment
  24. 2026-09-17 09:36 UTCGHSA enrichment
  25. 2026-09-17 05:25 UTCGHSA enrichment
Show 16 more
  1. 2026-09-17 01:15 UTCGHSA enrichment
  2. 2026-09-16 21:04 UTCEG score recompute
  3. 2026-09-16 21:04 UTCGHSA enrichment
  4. 2026-09-16 19:29 UTCEG score recompute
  5. 2026-09-16 19:29 UTCGHSA enrichment
  6. 2026-09-16 18:12 UTCEG score recompute
  7. 2026-09-16 18:12 UTCGHSA enrichment
  8. 2026-09-16 14:09 UTCEPSS rescore
  9. 2026-09-16 14:01 UTCGHSA enrichment
  10. 2026-09-16 09:49 UTCGHSA enrichment
  11. 2026-09-16 05:39 UTCGHSA enrichment
  12. 2026-09-16 01:29 UTCEG score recompute
  13. 2026-09-16 01:29 UTCGHSA enrichment
  14. 2026-09-15 21:18 UTCEG score recompute
  15. 2026-09-15 21:03 UTCEG score recompute
  16. 2026-09-15 21:02 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-91939?
CVE-2026-91939 is a critical vulnerability published on September 15, 2026. Cotonti 1.0.0 Comments plugin passes the ci GET parameter to unserialize() without allowed_classes restriction, allowing unauthenticated attackers to instantiate arbitrary PHP classes with attacker-controlled properties. Attackers can exploit PHP object injection through crafted serialized payloads…
When was CVE-2026-91939 disclosed?
CVE-2026-91939 was first published in the National Vulnerability Database on September 15, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91939 actively exploited?
CVE-2026-91939 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 52.9% of all scored CVEs.
What is the CVSS score of CVE-2026-91939?
CVE-2026-91939 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-91939?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-91939, 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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