CVE-2026-74934

HIGH 7.5CVE-2026-74934 · Published 18/08/2026 · updated 24/08/2026

In short

CVE-2026-74934 is a HIGH (CVSS 7.5) vulnerability affecting firefox (mozilla), thunderbird (mozilla).
Chance of exploitation in the next 30 days (EPSS): 0.21%, higher than 11.5% of all vulnerabilities.
Fix: update to 140.14.0, 153.1.0, 115.39.0 or later.

Package	Affected versions	Patched versions
firefox mozilla	`≥ 116.0, < 140.14.0≥ 141.0, < 153.1.0< 115.39.0`	`140.14.0153.1.0115.39.0`
thunderbird mozilla	`≥ 141.0, < 153.1.0< 140.14.0`	`153.1.0140.14.0`

Description

Site isolation issue in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

References

bugzilla.mozilla.org/show_bug.cgi · Permissions Required
mozilla.org/security/advisories/mfsa2026-74 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-75 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-76 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-77 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-78 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-79 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-80 · Vendor Advisory

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Package

Affected versions

Patched versions

firefox

mozilla

≥ 116.0, < 140.14.0≥ 141.0, < 153.1.0< 115.39.0

140.14.0153.1.0115.39.0

thunderbird

mozilla

≥ 141.0, < 153.1.0< 140.14.0

153.1.0140.14.0

More vulnerabilities in firefox

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