CVE-2026-92040: Use-after-free in the JavaScript: WebAssembly component
Analyzed
AliasesUBUNTU-CVE-2026-92040
Published 15-09-2026Last modified 20-09-2026
Vulnerability summary
CVE-2026-92040 is a high (CVSS 8.8) Use After Free vulnerability in mozilla firefox. EPSS estimates a 0.42% chance of exploitation in the next 30 days, higher than 35.4% of scored vulnerabilities.
CVSS score
8.8/10
010
High · v3.1 (CVE.org)EPSS score
0.42%
0%100%
Low · +0.12 pp in 30 daysKEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 1 · Related 1Timeline
- 15-09-2026PublishedVulnerability first disclosed.
- 20-09-2026Last modifiedVulnerability information updated.
Description
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.
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
0.42%
Chance of exploitation in the next 30 days
Percentile
35%
Versus all other CVEs
30-day change
Increase +0.12 pp
From 0.30% on 22-09-2026
22-09-202622-10-2026
Known exploited
Compare KEV catalogsNot in the CISA KEV catalog.
Not in the ENISA CNW catalog.
Not in the CIRCL catalog.
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< 156.0.0
- thunderbird< 156.0
2 vendors · 10 products
References
6 links- bugzilla.mozilla.org/show_bug.cgi?id=2024248Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-90/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-94/Vendor Advisory