CVE-2026-74960
Medium
Elevated severity or exploit probability.
CVSS base
8.1
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
EPSS — probability of exploitation (30 days)
0.2%
6.0th percentile
CISA KEV
Not listed
Weakness / dates
CWE-284
Published 2026-08-18 · modified 2026-08-24
CVSS breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
| Attack Vector | N | Network |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | R | Required |
| Scope | U | Unchanged |
| Confidentiality | H | High |
| Integrity | H | High |
| Availability | N | None |
Timeline
- 2026-08-18 — Published (NVD)
- 2026-08-24 — Last modified (NVD)
Description
Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
Affected
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2049148
- https://www.mozilla.org/security/advisories/mfsa2026-74/
- https://www.mozilla.org/security/advisories/mfsa2026-76/
- https://www.mozilla.org/security/advisories/mfsa2026-77/
- https://www.mozilla.org/security/advisories/mfsa2026-78/
- https://www.mozilla.org/security/advisories/mfsa2026-79/
- https://www.mozilla.org/security/advisories/mfsa2026-80/