Critical severity9.8NVD Advisory· Published Apr 7, 2026· Updated Apr 16, 2026
CVE-2026-5731
CVE-2026-5731
Description
Memory safety bugs present in Firefox ESR 115.34.0, Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
32cpe:2.3:a:mozilla:firefox:115.34.0:*:*:*:esr:*:*:*+ 2 more
- cpe:2.3:a:mozilla:firefox:115.34.0:*:*:*:esr:*:*:*
- cpe:2.3:a:mozilla:firefox:140.9.0:*:*:*:esr:*:*:*
- cpe:2.3:a:mozilla:firefox:149.0.1:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:140.9.0:*:*:*:esr:*:*:*+ 1 more
- cpe:2.3:a:mozilla:thunderbird:140.9.0:*:*:*:esr:*:*:*
- cpe:2.3:a:mozilla:thunderbird:149.0.1:*:*:*:-:*:*:*
- osv-coords27 versionspkg:apk/chainguard/firefoxpkg:apk/chainguard/firefox-esrpkg:apk/wolfi/firefoxpkg:rpm/almalinux/firefoxpkg:rpm/almalinux/firefox-x11pkg:rpm/almalinux/thunderbirdpkg:rpm/opensuse/firefox-esr&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/MozillaThunderbird&distro=openSUSE%20Tumbleweedpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015%20SP4-ESPOSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015%20SP4-LTSSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015%20SP5-ESPOSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015%20SP5-LTSSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Desktop%20Applications%2015%20SP7pkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP5-LTSSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%2015%20SP4-LTSSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%2015%20SP5-LTSSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%2015%20SP6-LTSSpkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%2016.0pkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2015%20SP4pkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2015%20SP5pkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2015%20SP6pkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20applications%2016.0pkg:rpm/suse/MozillaFirefox&distro=SUSE%20Linux%20Enterprise%20Server%20LTSS%20Extended%20Security%2012%20SP5pkg:rpm/suse/MozillaThunderbird&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Package%20Hub%2015%20SP7pkg:rpm/suse/MozillaThunderbird&distro=SUSE%20Linux%20Enterprise%20Workstation%20Extension%2015%20SP7
< 151.0.2-r0+ 26 more
- (no CPE)range: < 151.0.2-r0
- (no CPE)range: < 115.34.1-r0
- (no CPE)range: < 151.0.2-r0
- (no CPE)range: < 140.9.1-1.el9_7.alma.1
- (no CPE)range: < 140.9.1-1.el9_7.alma.1
- (no CPE)range: < 140.9.1-1.el9_7.alma.1
- (no CPE)range: < 140.9.1-1.1
- (no CPE)range: < 140.9.1-160000.1.1
- (no CPE)range: < 149.0.2-1.1
- (no CPE)range: < 140.9.1-1.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-112.307.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-160000.1.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-150200.152.228.1
- (no CPE)range: < 140.9.1-160000.1.1
- (no CPE)range: < 140.9.1-112.307.1
- (no CPE)range: < 140.9.1-150200.8.266.1
- (no CPE)range: < 140.9.1-150200.8.266.1
Patches
Vulnerability mechanics
References
6- www.mozilla.org/security/advisories/mfsa2026-25/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-26/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-27/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-28/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-29/nvdVendor Advisory
- bugzilla.mozilla.org/buglist.cginvdBroken Link
News mentions
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