XSS in Mozilla Firefox
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.010 (60.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
Affected products
- Mozilla Firefox — versions < 83
- Mozilla Firefox Esr — versions < 78.5
- Mozilla Firefox_esr
- Mozilla Thunderbird — versions < 78.5
Weakness classification (CWE)
References
- security@mozilla.org (Permissions Required, x_refsource_MISC, Issue Tracking, Vendor Advisory)
- security@mozilla.org (x_refsource_CONFIRM, Vendor Advisory)
- security@mozilla.org (x_refsource_CONFIRM, Vendor Advisory)
- security@mozilla.org (x_refsource_CONFIRM, Vendor Advisory)
Frequently asked questions
- What is CVE-2020-26951?
- CVE-2020-26951 is a medium-severity vulnerability in Mozilla Firefox, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2020-12-09.
- How severe is CVE-2020-26951?
- Medium severity. CVSS v3 base score is 6.1 out of 10.