CVE-2020-26950

In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.

• CWE-416

• http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.htmlExploit, Third Party Advisory, VDB Entry
• https://bugzilla.mozilla.org/show_bug.cgi?id=1675905Exploit, Issue Tracking, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-49/Vendor Advisory
• http://packetstormsecurity.com/files/166175/Firefox-MCallGetProperty-Write-Side-Effects-Use-After-Free.htmlExploit, Third Party Advisory, VDB Entry
• https://bugzilla.mozilla.org/show_bug.cgi?id=1675905Exploit, Issue Tracking, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-49/Vendor Advisory

Published

Dec 9, 2020

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2020-26943An issue was discovered in OpenStack blazar-dashboard before…9.9
• CVE-2020-26944An issue was discovered in Aptean Product Configurator 4.61.…9.8
• CVE-2020-26945MyBatis before 3.5.6 mishandles deserialization of object st…8.1
• CVE-2020-26947monero-wallet-gui in Monero GUI before 0.17.1.0 includes the…7.8
• CVE-2020-26948Emby Server before 4.5.0 allows SSRF via the Items/RemoteSea…9.8
• CVE-2020-2695Vulnerability in the PeopleSoft Enterprise CC Common Applica…5.3
• CVE-2020-26951A parsing and event loading mismatch in Firefox's SVG code c…6.1
• CVE-2020-26952Incorrect bookkeeping of functions inlined during JIT compil…8.8
• CVE-2020-26953It was possible to cause the browser to enter fullscreen mod…4.3
• CVE-2020-26954When accepting a malicious intent from other installed apps,…4.3
• CVE-2020-26955When a user downloaded a file in Firefox for Android, if a c…6.5
• CVE-2020-26956In some cases, removing HTML elements during sanitization wo…6.1