CVE-2026-12311mediumCWE-200 CWE-688

CVE-2026-12311: medium-severity vulnerability in Mozilla Firefox

Information disclosure, sandbox escape in the Security: Process Sandboxing component

Published 16 Jun 2026

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 4.7epss 0.2%

Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

Affected products

Mozilla · Firefox Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=2040177 https://www.mozilla.org/security/advisories/mfsa2026-57/https://www.mozilla.org/security/advisories/mfsa2026-58/https://www.mozilla.org/security/advisories/mfsa2026-60/https://www.mozilla.org/security/advisories/mfsa2026-61/