CVE-2026-84123: mozilla firefox Use After Free
CVSS: 8.8v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-84123CGA-6mcr-mq32-q9wvCGA-h2v3-4fvp-9cc7CGA-rh7p-x9v9-pp2jCGA-w9g8-p5w9-w29j
Published 01-09-2026Last modified 02-09-2026
Vulnerability summary
CVE-2026-84123 is a high (CVSS 8.8) Use After Free vulnerability in mozilla firefox. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 36.5% of scored vulnerabilities.
CVSS score
8.8/10
010
High · v3.1 (CVE.org)EPSS score
0.44%
0%100%
Low · +0.20 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 10 · Related 9Timeline
- 01-09-2026PublishedVulnerability first disclosed.
- 02-09-2026Last modifiedVulnerability information updated.
Description
Privilege escalation due to use-after-free in the Graphics: WebGPU component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
CVSS metrics
3 scores · 3 sources · 1 versionHigh 8.8Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated8.8HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- NVDNIST8.8HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.44%
Chance of exploitation in the next 30 days
Percentile
37%
Versus all other CVEs
30-day change
+0.20 pp
From 0.23% on 19-09-2026
19-09-202619-10-2026
EPSS score0.44%
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)
Chainguard2 products
- firefox< 155.0.1-r0
- firefox-docker-selenium-compat< 155.0.1-r0
Mozilla2 products
- firefox< 153.2.0 | ≥ 154.0.0, < 155.0.0
- thunderbird< 153.2.0 | ≥ 154.0, < 155.0
Wolfi2 products
- firefox< 155.0.1-r0
- firefox-docker-selenium-compat< 155.0.1-r0
4 vendors · 14 products
References
8 links- bugzilla.mozilla.org/show_bug.cgi?id=2060047Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-82/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-85/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-86/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-88/Vendor Advisory