CVE-2026-92079: mozilla firefox Protection Mechanism Failure
CVSS: 9.1v3.1CriticalAnalyzed
AliasesUBUNTU-CVE-2026-92079
Published 15-09-2026Last modified 22-09-2026
Vulnerability summary
CVE-2026-92079 is a critical (CVSS 9.1) Protection Mechanism Failure vulnerability in mozilla firefox. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 15.5% of scored vulnerabilities.
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)EPSS score
0.25%
0%100%
Low · +0.10 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 8 · Related 8Timeline
- 15-09-2026PublishedVulnerability first disclosed.
- 22-09-2026Last modifiedVulnerability information updated.
Description
Mitigation bypass in the Widget: Win32 component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.
CVSS metrics
3 scores · 3 sources · 1 versionCritical 9.1Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- NVDNIST9.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS trend
Probability
0.25%
Chance of exploitation in the next 30 days
Percentile
16%
Versus all other CVEs
30-day change
+0.10 pp
From 0.15% on 21-09-2026
21-09-202621-10-2026
EPSS score0.25%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu8 products
- mozjs102All versions (No fix recorded)
- mozjs115All versions (No fix recorded)
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
Mozilla2 products
- firefox< 153.3.0 | ≥ 154.0.0, < 156.0.0
- thunderbird< 153.3.0 | ≥ 154.0, < 156.0
2 vendors · 10 products
References
8 links- bugzilla.mozilla.org/show_bug.cgi?id=2067531Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-90/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-93/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-94/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-96/Vendor Advisory