CVE-2026-7321: Mozilla Firefox · Buffer Overflow
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 9.6 Critical · patch available : patch Mozilla Firefox as a priority.
Data as of 30 Oct 2026, 11:52 UTC
Contested
Critical score, yet low EPSS after six months- EPSS
- 0.2% chance of exploitation in 30 days – higher than 17% 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:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 28 Apr 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
Mozilla has released official fixes for this vulnerability in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1. Users and administrators should apply these updates promptly to remediate the issue. Since this is not a cloud service, remediation depends on user-side patching. There are no vendor advisories indicating that no action is required or that the issue is already mitigated without patching.
Description
Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2029461 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-30/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-33/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-36/ (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-39/ (opens in a new tab)