CVE-2026-100761: mozilla firefox Use After Free
CVSS: 8.8v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-100761
Published 29-09-2026Last modified 30-09-2026
Vulnerability summary
CVE-2026-100761 is a high (CVSS 8.8) Use After Free vulnerability in mozilla firefox. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 12.4% of scored vulnerabilities.
CVSS score
8.8/10
010
High · v3.1 (CVE.org)EPSS score
0.22%
0%100%
Low · Change unavailableKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 1 · Related 1Timeline
- 29-09-2026PublishedVulnerability first disclosed.
- 30-09-2026Last modifiedVulnerability information updated.
Description
Privilege escalation due to use-after-free in the Graphics: WebGPU component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.
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
0.22%
Chance of exploitation in the next 30 days
Percentile
12%
Versus all other CVEs
30-day change
Change unavailable
Change unavailable
30-09-202621-10-2026
EPSS score0.22%
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< 157.0.0
- thunderbird< 157.0
2 vendors · 10 products
References
6 links- www.mozilla.org/security/advisories/mfsa2026-101/Vendor Advisory