CVE-2026-100777: Vulnerability in Mozilla Firefox
Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
AI Analysis
Technical Summary
This vulnerability involves a use-after-free condition in the Graphics: Canvas2D component of Mozilla Firefox. Use-after-free vulnerabilities occur when a program continues to use a pointer after the memory it points to has been freed, potentially leading to arbitrary code execution or crashes. Mozilla has addressed this issue by releasing fixes in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. The advisory categorizes the impact as high and lists this vulnerability among multiple high-impact security fixes.
Potential Impact
The vulnerability is rated with high impact by Mozilla, indicating that exploitation could lead to significant security consequences such as arbitrary code execution or application crashes. However, there are no known active exploits in the wild at the time of the advisory.
Mitigation Recommendations
A fix is available and has been released in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. Users and administrators should update affected Firefox installations to these versions or later to remediate this vulnerability.
CVE-2026-100777: Vulnerability in Mozilla Firefox
Description
Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.
CVSS v3.1
Score 8.8high
Affected software
Mozilla
Firefox
pkg:github/mozilla/firefoxRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves a use-after-free condition in the Graphics: Canvas2D component of Mozilla Firefox. Use-after-free vulnerabilities occur when a program continues to use a pointer after the memory it points to has been freed, potentially leading to arbitrary code execution or crashes. Mozilla has addressed this issue by releasing fixes in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. The advisory categorizes the impact as high and lists this vulnerability among multiple high-impact security fixes.
Potential Impact
The vulnerability is rated with high impact by Mozilla, indicating that exploitation could lead to significant security consequences such as arbitrary code execution or application crashes. However, there are no known active exploits in the wild at the time of the advisory.
Mitigation Recommendations
A fix is available and has been released in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. Users and administrators should update affected Firefox installations to these versions or later to remediate this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mozilla
- Date Reserved
- 2026-09-26T19:16:45.611Z
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://www.mozilla.org/security/advisories/mfsa2026-100/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-97/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-98/","vendor":"Mozilla"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-99/","vendor":"Mozilla"}]
Threat ID: 6abbb3eff7a7c5410664097a
Added to database: 09/29/2026, 12:49:51 UTC
Last enriched: 09/29/2026, 13:32:56 UTC
Last updated: 09/29/2026, 18:20:12 UTC
Views: 2
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.