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VulnerabilityPublished Updated

CVE-2026-8389: Mozilla Firefox · CWE-686

Affects Mozilla FirefoxSource CVE Database V5

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Not known to be exploited · CVSS 8.8 High : upgrade to 150.0.3 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 36% 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:R/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade mozilla/firefox to 150.0.3.

Affected software

ProductAffectedFixed in
GitHubmozilla/firefoxpkg:github/mozilla/firefoxOther threatsAffected
  • <150.0.3
Fixed in
  • 150.0.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available and included in Mozilla Firefox version 150.0.3. Users and administrators should update affected Firefox installations to version 150.0.3 or later to remediate this vulnerability. No additional mitigation steps are indicated by the vendor advisory.

Description

JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 150.0.3.

References

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