CVE-2020-26959

During browser shutdown, reference decrementing could have occured on a previously freed object, resulting in a use-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

• CWE-416

• https://bugzilla.mozilla.org/show_bug.cgi?id=1669466Issue Tracking, Permissions Required, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-50/Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-51/Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-52/Vendor Advisory
• https://bugzilla.mozilla.org/show_bug.cgi?id=1669466Issue Tracking, Permissions Required, Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-50/Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-51/Vendor Advisory
• https://www.mozilla.org/security/advisories/mfsa2020-52/Vendor Advisory

Published

Dec 9, 2020

Last Modified

Jun 17, 2026

Status

Modified

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