CVE-2026-8955: Mozilla Firefox · Improper Privilege Management
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 8.8 High · patch available : patch Mozilla Firefox soon.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 32% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
This vulnerability has been fixed in Firefox 151 and Firefox ESR 140.11. Users and administrators should update to these versions or later to remediate the issue. Since this is not a cloud service, manual patching is required. No additional mitigation steps are indicated by the vendor advisories.
Description
CVE-2026-8955 is a privilege escalation vulnerability in the DOM: Workers component of Mozilla Firefox. This vulnerability was addressed and fixed in Firefox 151 and Firefox ESR 140.11. It has a high severity rating with a CVSS score of 8.8, indicating it could allow an attacker to gain elevated privileges. The vendor advisories confirm the issue and the availability of fixes in the specified Firefox versions.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2031064 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-46/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-48/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-50/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-51/ (opens in a new tab)