CVE-2026-12315

CRITICAL 9.1CVE-2026-12315 · Published 16/06/2026 · updated 26/10/2026

In short

CVE-2026-12315 is a CRITICAL (CVSS 9.1) vulnerability affecting firefox (mozilla), thunderbird (mozilla).
Chance of exploitation in the next 30 days (EPSS): 0.25%, higher than 16.5% of all vulnerabilities.
Fix: update to 140.12.0, 152.0.0 or later.

Package	Affected versions	Patched versions
firefox mozilla	`< 140.12.0< 152.0.0`	`140.12.0152.0.0`
thunderbird mozilla	`< 140.12.0< 152.0.0`	`140.12.0152.0.0`

Description

Mitigation bypass in the DOM: Security 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

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Package

Affected versions

Patched versions

firefox

mozilla

< 140.12.0< 152.0.0

140.12.0152.0.0

thunderbird

mozilla

< 140.12.0< 152.0.0

140.12.0152.0.0

More vulnerabilities in firefox

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