CVE-2026-16387

CRITICAL 9.8CVE-2026-16387 · Published 21/07/2026 · updated 24/10/2026

Package	Affected versions	Patched versions
firefox mozilla	`< 140.13.0< 153.0.0`	`140.13.0153.0.0`
thunderbird mozilla	`≥ 141.0, < 153.0< 140.13.0`	`153.0140.13.0`

Description

Site isolation issue in the Networking component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.

References

bugzilla.mozilla.org/show_bug.cgi · Permissions Required
mozilla.org/security/advisories/mfsa2026-68 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-70 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-71 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-72 · Vendor Advisory

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