Detections
Analytics
CVE-2026-4721
high
Description
Memory safety bugs present in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. 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, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
References
https://www.mozilla.org/security/advisories/mfsa2026-24/
https://www.mozilla.org/security/advisories/mfsa2026-23/
https://www.mozilla.org/security/advisories/mfsa2026-22/
https://www.mozilla.org/security/advisories/mfsa2026-21/
https://www.mozilla.org/security/advisories/mfsa2026-20/
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4721.json
https://bugzilla.redhat.com/show_bug.cgi?id=2450711
https://access.redhat.com/security/cve/CVE-2026-4721
https://access.redhat.com/errata/RHSA-2026:8850
https://access.redhat.com/errata/RHSA-2026:8427
https://access.redhat.com/errata/RHSA-2026:8315
https://access.redhat.com/errata/RHSA-2026:8290
https://access.redhat.com/errata/RHSA-2026:8289
https://access.redhat.com/errata/RHSA-2026:8288
https://access.redhat.com/errata/RHSA-2026:8287
https://access.redhat.com/errata/RHSA-2026:8286
https://access.redhat.com/errata/RHSA-2026:8285
https://access.redhat.com/errata/RHSA-2026:8284
https://access.redhat.com/errata/RHSA-2026:7858
https://access.redhat.com/errata/RHSA-2026:7845
https://access.redhat.com/errata/RHSA-2026:7843
https://access.redhat.com/errata/RHSA-2026:7842
https://access.redhat.com/errata/RHSA-2026:7841
https://access.redhat.com/errata/RHSA-2026:7840
https://access.redhat.com/errata/RHSA-2026:7839
https://access.redhat.com/errata/RHSA-2026:7838
https://access.redhat.com/errata/RHSA-2026:7837
https://access.redhat.com/errata/RHSA-2026:6917
https://access.redhat.com/errata/RHSA-2026:6342
https://access.redhat.com/errata/RHSA-2026:6188
https://access.redhat.com/errata/RHSA-2026:5932