CVE-2026-8948
CRITICAL 9.1Same-origin policy bypass in the DOM: Networking component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.
ELEVATED IMPACT
Severe if exploited (CVSS 9.1), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 34th percentile
○ In CISA KEV
○ Public exploit / PoC
Impact if exploited
9.1CVSS 3.1 · CRITICAL
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Affected
Products Firefox Thunderbird Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9
Weakness (CWE)
- CWE-942
- CWE-79: Cross-site scripting (XSS)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
References
Technical & other
- https://bugzilla.mozilla.org/show_bug.cgi?id=2038803
- https://www.mozilla.org/security/advisories/mfsa2026-46/
- https://www.mozilla.org/security/advisories/mfsa2026-50/
- https://access.redhat.com/security/cve/CVE-2026-8948
- https://bugzilla.redhat.com/show_bug.cgi?id=2479850
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8948.json