by Kastro
Paper/Archive/CVE-2025-6427

CVE-2025-6427

Mozilla Firefox — connect-src Content Security Policy restriction could be bypassed

EPSS 0.4%CVSS 9.1
critical.is priorityof 100
33
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 30.7.307 × 206.1No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
Firefoxsee advisory140CNA
Thunderbirdsee advisory140CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refbugzilla.mozilla.org/show_bug.cgi?id=1966927refmozilla.org/security/advisories/mfsa2025-51refmozilla.org/security/advisories/mfsa2025-54