CVE-2026-84120
Low
No strong exploitation signal.
CVSS base
5.4
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
EPSS — probability of exploitation (30 days)
0.2%
12.7th percentile
CISA KEV
Not listed
Weakness / dates
CWE-416
Published 2026-09-01 · modified 2026-09-02
CVSS breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
| Attack Vector | N | Network |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | R | Required |
| Scope | U | Unchanged |
| Confidentiality | L | Low |
| Integrity | L | Low |
| Availability | N | None |
Timeline
- 2026-09-01 — Published (NVD)
- 2026-09-02 — Last modified (NVD)
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
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2058911
- https://www.mozilla.org/security/advisories/mfsa2026-82/
- https://www.mozilla.org/security/advisories/mfsa2026-83/
- https://www.mozilla.org/security/advisories/mfsa2026-84/
- https://www.mozilla.org/security/advisories/mfsa2026-85/
- https://www.mozilla.org/security/advisories/mfsa2026-86/
- https://www.mozilla.org/security/advisories/mfsa2026-87/
- https://www.mozilla.org/security/advisories/mfsa2026-88/