CVE-2026-74979

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-18. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 5 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

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

Mitigation bypass in the Add-ons Manager component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 20, 2026

Advisory Details (5)

Auto-updated Aug 20, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Thunderbird 153.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-80/
generic

Security Vulnerabilities fixed in Thunderbird 154 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-78/
generic

Security Vulnerabilities fixed in Firefox ESR 153.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-77/
generic

Security Vulnerabilities fixed in Firefox 154 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-74/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2045676

Vendor Advisories for CVE-2026-74979(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 28× in last 7d / 28× 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. 2026-08-21 08:05 UTCGHSA enrichment
  2. 2026-08-21 04:03 UTCGHSA enrichment
  3. 2026-08-21 00:02 UTCEG score recompute
  4. 2026-08-21 00:02 UTCGHSA enrichment
  5. 2026-08-20 22:56 UTCEPSS rescore
  6. 2026-08-20 20:00 UTCGHSA enrichment
  7. 2026-08-20 19:50 UTCGHSA enrichment
  8. 2026-08-20 15:48 UTCGHSA enrichment
  9. 2026-08-20 11:46 UTCGHSA enrichment
  10. 2026-08-20 07:43 UTCGHSA enrichment
  11. 2026-08-20 03:42 UTCGHSA enrichment
  12. 2026-08-19 23:41 UTCGHSA enrichment
  13. 2026-08-19 19:39 UTCEG score recompute
  14. 2026-08-19 19:39 UTCGHSA enrichment
  15. 2026-08-19 17:04 UTCEPSS rescore
  16. 2026-08-19 15:37 UTCGHSA enrichment
  17. 2026-08-19 11:36 UTCGHSA enrichment
  18. 2026-08-19 07:32 UTCGHSA enrichment
  19. 2026-08-19 03:30 UTCGHSA enrichment
  20. 2026-08-18 23:27 UTCEG score recompute
  21. 2026-08-18 23:27 UTCGHSA enrichment
  22. 2026-08-18 19:24 UTCGHSA enrichment
  23. 2026-08-18 19:05 UTCEG score recompute▲ 9.80
  24. 2026-08-18 19:05 UTCGHSA enrichment
  25. 2026-08-18 19:04 UTCMITRE cvelistV5CVSS v3 → 9.8 · severity → CRITICAL
Show 3 more
  1. 2026-08-18 13:19 UTCNVD update
  2. 2026-08-18 12:42 UTCEG score recompute
  3. 2026-08-18 12:41 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-74979?
CVE-2026-74979 is a critical vulnerability published on August 18, 2026. Mitigation bypass in the Add-ons Manager component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
When was CVE-2026-74979 disclosed?
CVE-2026-74979 was first published in the National Vulnerability Database on August 18, 2026, with the most recent update on August 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-74979 actively exploited?
CVE-2026-74979 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 72.0% of all scored CVEs.
What is the CVSS score of CVE-2026-74979?
CVE-2026-74979 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-74979?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-74979, 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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