CVE-2026-74934: Vulnerability in Mozilla Firefox
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.
AI Analysis
Technical Summary
CVE-2026-74934 is a security vulnerability involving a site isolation issue within the Graphics: CanvasWebGL component of Mozilla Firefox. Site isolation is a security feature designed to separate web content from different origins into different processes to prevent data leaks and privilege escalation. This vulnerability could potentially undermine that isolation. Mozilla fixed this vulnerability in Firefox 154 and Firefox ESR versions 115.39, 140.14, and 153.1 as part of a broader set of security fixes addressing multiple high-impact issues. The vendor advisories confirm the fix and classify the impact as high.
Potential Impact
The vulnerability affects the site isolation mechanism in the CanvasWebGL graphics component, which could allow an attacker to bypass security boundaries between web content origins. This could lead to unauthorized access or privilege escalation within the browser context. Mozilla rates the impact as high. There are no reports of active exploitation in the wild at this time.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox 154 and Firefox ESR versions 115.39, 140.14, and 153.1. Users and administrators should update to these versions or later to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory.
CVE-2026-74934: Vulnerability in Mozilla Firefox
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.
Affected software
pkg:github/mozilla/firefox-esrRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-74934 is a security vulnerability involving a site isolation issue within the Graphics: CanvasWebGL component of Mozilla Firefox. Site isolation is a security feature designed to separate web content from different origins into different processes to prevent data leaks and privilege escalation. This vulnerability could potentially undermine that isolation. Mozilla fixed this vulnerability in Firefox 154 and Firefox ESR versions 115.39, 140.14, and 153.1 as part of a broader set of security fixes addressing multiple high-impact issues. The vendor advisories confirm the fix and classify the impact as high.
Potential Impact
The vulnerability affects the site isolation mechanism in the CanvasWebGL graphics component, which could allow an attacker to bypass security boundaries between web content origins. This could lead to unauthorized access or privilege escalation within the browser context. Mozilla rates the impact as high. There are no reports of active exploitation in the wild at this time.
Mitigation Recommendations
Mozilla has released official fixes for this vulnerability in Firefox 154 and Firefox ESR versions 115.39, 140.14, and 153.1. Users and administrators should update to these versions or later to mitigate the risk. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-08-17T11:57:25.126Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-74/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-75/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-76/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-77/","vendor":"Mozilla"}]
Threat ID: 6a845502c6e8be0332367397
Added to database: 08/18/2026, 12:50:10 UTC
Last enriched: 08/18/2026, 14:22:39 UTC
Last updated: 08/19/2026, 03:21:23 UTC
Views: 6
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