CVE-2020-26951

A parsing and event loading mismatch in Firefox's SVG code could have allowed load events to fire, even after sanitization. An attacker already capable of exploiting an XSS vulnerability in privileged internal pages could have used this attack to bypass our built-in sanitizer. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

• CWE-79

• https://bugzilla.mozilla.org/show_bug.cgi?id=1667113Issue 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=1667113Issue 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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