CVE-2026-8391
published 2026-05-12CVE-2026-8391: 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.
PriorityP426medium5.3CVSS 3.1
AVNACLPRNUINSUCLINAN
EPSS
0.30%
22.0th percentile
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.
Affected
5 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mozilla | firefox | < Firefox 150.0.3 | Firefox 150.0.3 |
| mozilla | firefox | < 150.0.3 | 150.0.3 |
| mozilla | firefox_esr | < Firefox ESR 115.36 | Firefox ESR 115.36 |
| mozilla | firefox_esr | < Firefox ESR 140.11 | Firefox ESR 140.11 |
| mozilla | thunderbird | < Thunderbird 140.11 | Thunderbird 140.11 |
CVSS provenance
nvdv3.15.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
vendor_redhat5.3MEDIUM
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
VulDB
Mozilla Firefox up to 150.0.2 JavaScript Engine input validation (EUVD-2026-29466 / Nessus ID 315326)
vuldb·2026-05-26·CVSS 5.3
CVE-2026-8391 [MEDIUM] Mozilla Firefox up to 150.0.2 JavaScript Engine input validation (EUVD-2026-29466 / Nessus ID 315326)
A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 150.0.2. Affected is an unknown function of the component JavaScript Engine. Performing a manipulation results in improper input validation.
This vulnerability is identified as CVE-2026-8391. The attack can be initiated remotely. There is not any exploit available.
It is advisable to upgrade the affected component.
GHSA
GHSA-93pv-vhrf-wv64: Other issue in the JavaScript Engine component
ghsa_unreviewed·2026-05-12
CVE-2026-8391 [MEDIUM] CWE-20 GHSA-93pv-vhrf-wv64: Other issue in the JavaScript Engine component
Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3.
Red Hat
firefox: Other issue in the JavaScript Engine component
vendor_redhat·2026-05-12·CVSS 5.3
CVE-2026-8391 [MEDIUM] CWE-475 firefox: Other issue in the JavaScript Engine component
firefox: Other issue in the JavaScript Engine component
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.
A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:
Other issue in the JavaScript Engine component
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: firefox (Red Hat Enterprise Linux 10) - Not affected
Package: rhel10/firefox-flatpak (Red Hat Enterprise Linux 10) - Not affected
Package: firefox (Red Hat Enterprise Linux 6) - Not affected
Package: firefox (Red Hat Enterprise Linux 7) - Not affected
Package: firefox (Red Hat Enterprise
Mozilla
Mozilla Foundation Security Advisory 2026-47: CVE-2026-8391
vendor_mozilla·CVSS 5.3
CVE-2026-8391 [MEDIUM] Mozilla Foundation Security Advisory 2026-47: CVE-2026-8391
Mozilla Foundation Security Advisory 2026-47
CVE: CVE-2026-8391
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 115.36
Mozilla
Mozilla Foundation Security Advisory 2026-48: CVE-2026-8391
vendor_mozilla·CVSS 5.3
CVE-2026-8391 [MEDIUM] Mozilla Foundation Security Advisory 2026-48: CVE-2026-8391
Mozilla Foundation Security Advisory 2026-48
CVE: CVE-2026-8391
Product: Firefox ESR
Impact: high
Fixed in: Firefox ESR 140.11
Mozilla
Mozilla Foundation Security Advisory 2026-51: CVE-2026-8391
vendor_mozilla·CVSS 5.3
CVE-2026-8391 [MEDIUM] Mozilla Foundation Security Advisory 2026-51: CVE-2026-8391
Mozilla Foundation Security Advisory 2026-51
CVE: CVE-2026-8391
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 140.11
Mozilla
Mozilla Foundation Security Advisory 2026-45: CVE-2026-8391
vendor_mozilla
CVE-2026-8391 Mozilla Foundation Security Advisory 2026-45: CVE-2026-8391
Mozilla Foundation Security Advisory 2026-45
CVE: CVE-2026-8391
Product: Firefox
Impact: high
Fixed in: Firefox 150.0.3
No detection rules found.
No public exploits indexed.
https://bugzilla.mozilla.org/show_bug.cgi?id=2038575https://www.mozilla.org/security/advisories/mfsa2026-45/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-2026:21378https://access.redhat.com/errata/RHSA-2026:21380https://access.redhat.com/errata/RHSA-2026:21381https://access.redhat.com/errata/RHSA-2026:21382https://access.redhat.com/errata/RHSA-2026:22325https://access.redhat.com/errata/RHSA-2026:22643https://access.redhat.com/errata/RHSA-2026:26174https://access.redhat.com/errata/RHSA-2026:26268https://access.redhat.com/errata/RHSA-2026:26269https://access.redhat.com/errata/RHSA-2026:26270https://access.redhat.com/errata/RHSA-2026:26491https://access.redhat.com/errata/RHSA-2026:26492https://access.redhat.com/errata/RHSA-2026:26493https://access.redhat.com/errata/RHSA-2026:26521https://access.redhat.com/errata/RHSA-2026:26536https://access.redhat.com/errata/RHSA-2026:26539https://access.redhat.com/errata/RHSA-2026:26551https://access.redhat.com/errata/RHSA-2026:26606https://access.redhat.com/errata/RHSA-2026:26629https://access.redhat.com/errata/RHSA-2026:26630https://access.redhat.com/errata/RHSA-2026:27715https://access.redhat.com/security/cve/CVE-2026-8391https://bugzilla.redhat.com/show_bug.cgi?id=2476475https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8391.json
2026-05-12
Published