Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
https://www.mozilla.org/security/advisories/mfsa2026-34/
https://www.mozilla.org/security/advisories/mfsa2026-33/
https://www.mozilla.org/security/advisories/mfsa2026-32/
https://www.mozilla.org/security/advisories/mfsa2026-31/
https://www.mozilla.org/security/advisories/mfsa2026-30/
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6754.json
https://bugzilla.redhat.com/show_bug.cgi?id=2460075
https://bugzilla.mozilla.org/show_bug.cgi?id=2027541
https://access.redhat.com/security/cve/CVE-2026-6754
https://access.redhat.com/errata/RHSA-2026:19704
https://access.redhat.com/errata/RHSA-2026:19655
https://access.redhat.com/errata/RHSA-2026:19542
https://access.redhat.com/errata/RHSA-2026:19469
https://access.redhat.com/errata/RHSA-2026:19468
https://access.redhat.com/errata/RHSA-2026:19467
https://access.redhat.com/errata/RHSA-2026:19466
https://access.redhat.com/errata/RHSA-2026:19465
https://access.redhat.com/errata/RHSA-2026:19464
https://access.redhat.com/errata/RHSA-2026:19463
https://access.redhat.com/errata/RHSA-2026:19462
https://access.redhat.com/errata/RHSA-2026:19461
https://access.redhat.com/errata/RHSA-2026:19348
https://access.redhat.com/errata/RHSA-2026:19201
https://access.redhat.com/errata/RHSA-2026:19131
https://access.redhat.com/errata/RHSA-2026:19041
https://access.redhat.com/errata/RHSA-2026:17690
https://access.redhat.com/errata/RHSA-2026:17689
https://access.redhat.com/errata/RHSA-2026:17688
https://access.redhat.com/errata/RHSA-2026:17687
https://access.redhat.com/errata/RHSA-2026:17477
https://access.redhat.com/errata/RHSA-2026:15892
https://access.redhat.com/errata/RHSA-2026:13537
https://access.redhat.com/errata/RHSA-2026:12285
https://access.redhat.com/errata/RHSA-2026:10767