CVE-2020-26951

MEDIUM

Firefox < 83.0 and Firefox ESR < 78.5 - Cross-Site Scripting via SVG Load Event Bypass

Title source: llm
STIX 2.1

Description

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.

References (4)

Core 4
Core References
Issue Tracking, Permissions Required, Vendor Advisory x_refsource_misc
https://bugzilla.mozilla.org/show_bug.cgi?id=1667113
Vendor Advisory x_refsource_confirm
https://www.mozilla.org/security/advisories/mfsa2020-50/
Vendor Advisory x_refsource_confirm
https://www.mozilla.org/security/advisories/mfsa2020-52/
Vendor Advisory x_refsource_confirm
https://www.mozilla.org/security/advisories/mfsa2020-51/

Scores

CVSS v3 6.1
EPSS 0.0043
EPSS Percentile 62.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Details

CWE
CWE-79
Status published
Products (3)
mozilla/firefox < 83.0
mozilla/firefox_esr < 78.5
mozilla/thunderbird < 78.5
Published Dec 09, 2020
Tracked Since Feb 18, 2026