CVE-2026-4684: Race condition, use-after-free in the Graphics: WebRender component
Vulnerability summary
CVE-2026-4684 is a high (CVSS 7.5) vulnerability in mozilla firefox. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 30.5% of scored vulnerabilities.
Not severe (CVSS 7.5, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 39 · Related 9Timeline
- 24-03-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
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 metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.37%
Chance of exploitation in the next 30 days
Percentile
31%
Versus all other CVEs
30-day change
Increase +0.01 pp
From 0.35% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-362Concurrent Execution using Shared Resource with Improper SynchronizationThe product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
- CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
- CWE-364Signal Handler Race ConditionThe product uses a signal handler that introduces a race condition.
Affected systems
Known conditions: network-reachable, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu8 products
- mozjs102All versions (No fix recorded)
- mozjs115All versions (No fix recorded)
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
Chainguard2 products
- firefox< 149.0-r0
- firefox-esr< 140.9.0-r0
Debian2 products
- firefox-esr< 140.9.0esr-1~deb12u1 | < 140.9.0esr-1~deb13u1 | < 140.9.0esr-1
- thunderbird< 1:140.9.0esr-1~deb12u1 | < 1:140.9.0esr-1~deb13u1 | < 1:140.9.0esr-1
Mozilla1 product
- firefox< 115.34.0 | < 149.0 | ≥ 128.0, < 140.9.0
Wolfi1 product
- firefox< 149.0-r0
5 vendors · 14 products
