CVE-2026-12311

MEDIUM 4.7CVE-2026-12311 · Published 16/06/2026 · updated 26/10/2026

In short

CVE-2026-12311 is a MEDIUM (CVSS 4.7) vulnerability affecting firefox (mozilla), thunderbird (mozilla).
Chance of exploitation in the next 30 days (EPSS): 0.18%, higher than 8.2% of all vulnerabilities.
Fix: update to 140.12.0, 152.0, 152.0.0 or later.

Package	Affected versions	Patched versions
firefox mozilla	`≥ 140.0, < 140.12.0< 152.0`	`140.12.0152.0`
thunderbird mozilla	`≥ 140.0, < 140.12.0< 152.0.0`	`140.12.0152.0.0`

Description

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.

References

bugzilla.mozilla.org/show_bug.cgi · Permissions Required
mozilla.org/security/advisories/mfsa2026-57 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-58 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-60 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-61 · Vendor Advisory

More vulnerabilities in firefox

See all →

Running one of these products? Scan your site to see whether it exposes a vulnerable version.

Scan my site free

Package

Affected versions

Patched versions

firefox

mozilla

≥ 140.0, < 140.12.0< 152.0

140.12.0152.0

thunderbird

mozilla

≥ 140.0, < 140.12.0< 152.0.0

140.12.0152.0.0

More vulnerabilities in firefox

See all →