CVE-2026-77991

CRITICALPre-NVD 9.49.4—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 66% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 4 sources updated this week
9.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.4Exploit: None knownExposed: 0

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

Joomla Extension - joomlaeventmanager.net - Privileged remote code execution in Joomla Event Manager < 5.0.1 - The administrator source model allows to write dangerous file type incl. PHP, leading to remote code execution.

CVSS v3
9.4
EG Score
9.4(medium)
EG Risk
42(Track)
EG Risk 42/100SSVC: Track

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
Severity94% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

August 27, 2026

Last Modified

August 28, 2026

Advisory Details (1)

Auto-updated Aug 28, 2026
No patch confirmed yet.
generic

JEM - Joomla Event Manager

https://www.joomlaeventmanager.net/

Vendor Advisories for CVE-2026-77991(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 26× in last 7d / 26× 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. 2026-08-29 23:34 UTCGHSA enrichment
  2. 2026-08-29 19:40 UTCGHSA enrichment
  3. 2026-08-29 15:46 UTCGHSA enrichment
  4. 2026-08-29 11:51 UTCGHSA enrichment
  5. 2026-08-29 07:51 UTCGHSA enrichment
  6. 2026-08-29 03:55 UTCGHSA enrichment
  7. 2026-08-28 23:57 UTCEG score recompute
  8. 2026-08-28 23:57 UTCGHSA enrichment
  9. 2026-08-28 21:42 UTCEPSS rescore
  10. 2026-08-28 16:14 UTCEG score recompute
  11. 2026-08-28 16:14 UTCGHSA enrichment
  12. 2026-08-28 13:05 UTCEG score recompute
  13. 2026-08-28 13:05 UTCGHSA enrichment
  14. 2026-08-28 09:10 UTCGHSA enrichment
  15. 2026-08-28 05:16 UTCGHSA enrichment
  16. 2026-08-28 01:18 UTCGHSA enrichment
  17. 2026-08-27 21:22 UTCGHSA enrichment
  18. 2026-08-27 17:28 UTCEG score recompute
  19. 2026-08-27 17:28 UTCGHSA enrichment
  20. 2026-08-27 14:25 UTCEPSS rescore
  21. 2026-08-27 14:23 UTCGHSA enrichment
  22. 2026-08-27 10:29 UTCGHSA enrichment
  23. 2026-08-27 06:34 UTCEG score recompute
  24. 2026-08-27 06:34 UTCGHSA enrichment
  25. 2026-08-27 06:13 UTCEG score recompute
Show 1 more
  1. 2026-08-27 06:11 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-77991?
CVE-2026-77991 is a critical vulnerability published on August 27, 2026. Joomla Extension - joomlaeventmanager.net - Privileged remote code execution in Joomla Event Manager < 5.0.1 - The administrator source model allows to write dangerous file type incl. PHP, leading to remote code execution.
When was CVE-2026-77991 disclosed?
CVE-2026-77991 was first published in the National Vulnerability Database on August 27, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77991 actively exploited?
CVE-2026-77991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 65.7% of all scored CVEs.
What is the CVSS score of CVE-2026-77991?
CVE-2026-77991 has a CVSS v3 base score of 9.4 (NVD).
How do I remediate CVE-2026-77991?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77991, 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-2026-77991

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