CVE-2020-26950

HighCVSS 8.8/10Last modified Jun 17, 2026

Description

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.

Metrics

CVSS 3.1 8.8/10CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Weakness enumeration

CWE-416

Affected software

Vendor	Product	Versions
Mozilla	Firefox	< 82.0.3
Mozilla	Firefox ESR	< 78.4.1
Mozilla	Thunderbird	< 78.4.2

References

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

Timeline

Published: Dec 9, 2020
Last modified: Jun 17, 2026
NVD status: Modified

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