Description
An attacker was able to bypass the `connect-src` directive of a Content Security Policy by manipulating subdocuments. This would have also hidden the connections from the Network tab in Devtools. This vulnerability was fixed in Firefox 140 and Thunderbird 140.
Affected products
mozilla: firefox
References3
- www.mozilla.org/security/advisories/mfsa2025-51/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=1966927 Permissions Required
- www.mozilla.org/security/advisories/mfsa2025-54/
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS — exploit probability
- 0% percentile: 31 · as of 7 November 2026
- CWE
- CWE-693
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