Medium severity5.4NVD Advisory· Published Sep 1, 2026· Updated Sep 2, 2026
CVE-2026-84120
CVE-2026-84120
Description
Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Affected products
13- Range: before 155
- Range: before 155
- osv-coords11 versionspkg:apk/chainguard/firefoxpkg:apk/chainguard/firefox-docker-selenium-compatpkg:apk/wolfi/firefoxpkg:apk/wolfi/firefox-docker-selenium-compatpkg:rpm/almalinux/firefoxpkg:rpm/almalinux/firefox-x11pkg:rpm/almalinux/thunderbirdpkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/MozillaThunderbird&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/firefox-esr&distro=openSUSE%20Tumbleweed
< 155.0.1-r0+ 10 more
- (no CPE)range: < 155.0.1-r0
- (no CPE)range: < 155.0.1-r0
- (no CPE)range: < 155.0.1-r0
- (no CPE)range: < 155.0.1-r0
- (no CPE)range: < 140.15.0-1.el10_2
- (no CPE)range: < 140.15.0-1.el9_8.alma.1
- (no CPE)range: < 140.16.0-1.el9_8.alma.1
- (no CPE)range: < 153.2.0-160000.1.1
- (no CPE)range: < 155.0-1.1
- (no CPE)range: < 140.15.0-1.1
- (no CPE)range: < 153.2.0-1.1
Patches
Vulnerability mechanics
References
8- www.mozilla.org/security/advisories/mfsa2026-82/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-83/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-84/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-85/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-86/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-87/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-88/nvdVendor Advisory
- bugzilla.mozilla.org/show_bug.cginvdPermissions Required
News mentions
2- ⚡ Weekly Recap: Chrome 0-Day, Router Hijacks, Coder Supply Chain Attack and MoreThe Hacker News · Sep 7, 2026
- Mozilla Firefox & Thunderbird: 25 Vulnerabilities Including Critical Sandbox Escapes Disclosed TogetherVypr Intelligence · Sep 1, 2026