CVE-2025-5270

In certain cases, SNI could have been sent unencrypted even when encrypted DNS was enabled. This vulnerability was fixed in Firefox 139 and Thunderbird 139.

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 20% of CVEs (scores of 2026-10-25)

CWE

CWE-319

Published

2025-05-27

Modified

2026-09-30

Record from

the NVD, synced 2026-10-19

Affected

• mozilla:firefox

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1910298
• https://www.mozilla.org/security/advisories/mfsa2025-42/
• https://www.mozilla.org/security/advisories/mfsa2025-45/

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