CVE-2026-4721
CRITICALCVSS v3.1: 9.8 · EPSS: 0.0043 (34.5 percentile)
Source data as of:
At a glance
- Severity
- CRITICAL
- CVSS
- 9.8 v3.1 · NVD
- EPSS
- 0.0043 (34.5 percentile) · FIRST.org
- CISA KEV
- No
- Type
- Buffer Overflow · NVD CWE
- Attack conditions (CVSS vector)
- NetworkNo privilegesNo user interaction · Source: NVD Vector
- Affected vendors
- mozilla
- Published
- 2026-03-24 · Modified: 2026-06-30
- References
- Jump to references (8)
CVSS / EPSS / KEV
Source — CVSS: NVD · EPSS: FIRST.org · KEV: CISA. Data & Sources
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
Reference URLs as listed by NVD, grouped by a mechanical match on the link's host/pattern. Labels describe the link type only.
- Reference https://bugzilla.mozilla.org/buglist.cgi?bug_id=2013762%2C2015291%2C2016591%2C2016661%2C20…
- Vendor advisory https://www.mozilla.org/security/advisories/mfsa2026-20/
- Vendor advisory https://www.mozilla.org/security/advisories/mfsa2026-21/
- Vendor advisory https://www.mozilla.org/security/advisories/mfsa2026-22/
- Vendor advisory https://www.mozilla.org/security/advisories/mfsa2026-23/
- Vendor advisory https://www.mozilla.org/security/advisories/mfsa2026-24/
- Distro https://access.redhat.com/errata/RHSA-2026:5930
- Distro https://access.redhat.com/errata/RHSA-2026:5931