CVE-2026-4684 — Race Condition in Mozilla Firefox

CWE-362 — Race ConditionCWE-416 — Use After FreeCWE-364 — Signal Handler Race Condition14 documents9 sources
Severity
7.5HIGHNVD
EPSS
0.0%
top 97.19%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla ThunderbirdMozilla Firefox
Timeline
PublishedMar 24

Description

Race condition, use-after-free in the Graphics: WebRender component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HExploitability: 1.6 | Impact: 5.9

Affected Packages2 packages

▶NVDmozilla/firefox128.0 — 140.9.0+2
▶Debianmozilla/thunderbird< 1:140.9.0esr-1~deb11u1+3

🔴Vulnerability Details

3
GHSA
GHSA-3rrq-fwhx-9wq4: Race condition, use-after-free in the Graphics: WebRender component↗2026-03-24
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OSV
CVE-2026-4684: Race condition, use-after-free in the Graphics: WebRender component↗2026-03-24
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CVEList
Race condition, use-after-free in the Graphics: WebRender component↗2026-03-24
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📋Vendor Advisories

7
Red Hat
firefox: thunderbird: Race condition, use-after-free in the Graphics: WebRender component↗2026-03-24
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Debian
CVE-2026-4684: firefox - Race condition, use-after-free in the Graphics: WebRender component. This vulner...↗2026
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Mozilla
Mozilla Foundation Security Advisory 2026-23: CVE-2026-4684↗
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Mozilla
Mozilla Foundation Security Advisory 2026-21: CVE-2026-4684↗
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Mozilla
Mozilla Foundation Security Advisory 2026-20: CVE-2026-4684↗
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🕵️Threat Intelligence

1
Wiz
CVE-2026-4684 Impact, Exploitability, and Mitigation Steps | Wiz↗
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💬Community

1
Bugzilla
CVE-2026-4684 firefox: thunderbird: Race condition, use-after-free in the Graphics: WebRender component↗2026-03-24
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CVE-2026-4684 — Race Condition in Mozilla Firefox | cvebase