VulnerabilityModified
CVE-2026-8391
This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.
MEDIUM 5.3EPSS 0.30%
Does this matter?
Lower severity and a low EPSS score (0.30%). Track it; it rarely justifies an emergency change on its own.
Description
Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.
- CVSS 3.1
- 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- EPSS
- 0.30% probability · 22th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-20, CWE-79, CWE-119, CWE-475
- Affected
- mozilla/firefox
- Source
- security@mozilla.org
EPSS 0.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2038575Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-45/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-47/
- https://www.mozilla.org/security/advisories/mfsa2026-48/
- https://www.mozilla.org/security/advisories/mfsa2026-51/
- https://access.redhat.com/errata/RHSA-2026:21378
- https://access.redhat.com/errata/RHSA-2026:21380
- https://access.redhat.com/errata/RHSA-2026:21381
- https://access.redhat.com/errata/RHSA-2026:21382
- https://access.redhat.com/errata/RHSA-2026:22325
- https://access.redhat.com/errata/RHSA-2026:22643
- https://access.redhat.com/errata/RHSA-2026:26174
- https://access.redhat.com/errata/RHSA-2026:26268
- https://access.redhat.com/errata/RHSA-2026:26269
- https://access.redhat.com/errata/RHSA-2026:26270
- https://access.redhat.com/errata/RHSA-2026:26491
- https://access.redhat.com/errata/RHSA-2026:26492
- https://access.redhat.com/errata/RHSA-2026:26493
- https://access.redhat.com/errata/RHSA-2026:26521
- https://access.redhat.com/errata/RHSA-2026:26536
- https://access.redhat.com/errata/RHSA-2026:26539
- https://access.redhat.com/errata/RHSA-2026:26551
- https://access.redhat.com/errata/RHSA-2026:26606
- https://access.redhat.com/errata/RHSA-2026:26629
- https://access.redhat.com/errata/RHSA-2026:26630
- https://access.redhat.com/errata/RHSA-2026:27715
- https://access.redhat.com/security/cve/CVE-2026-8391
- https://bugzilla.redhat.com/show_bug.cgi?id=2476475
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8391.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.