CVE-2026-8390: Mozilla Firefox · Use After Free
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 7.3 High · fixed in 150.0.3 : patch Mozilla Firefox soon.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 150.0.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:LExploitation evidence
Disclosed: evidence found.
CVE published 12 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 29 Oct 2026.
What to do
AI-suggested
Mozilla has released an official fix for this vulnerability in Firefox version 150.0.3. Users and administrators should update affected Firefox installations to version 150.0.3 or later to remediate this issue. There are no indications that additional mitigations are required beyond applying this update.
Description
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 150.0.3.
References
- bugzilla.mozilla.org/show_bug.cgi?id=2038081 (opens in a new tab)
- mozilla.org/security/advisories/mfsa2026-45/ (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-8390 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2476474 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8390.json (opens in a new tab)