XSS in Mozilla Firefox
CVE-2020-26956
In some cases, removing HTML elements during sanitization would keep existing SVG event handlers and therefore lead to XSS. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.012 (67.9th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 67.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000
Affected products
- Mozilla Firefox — versions < 83
- Mozilla Firefox Esr — versions < 78.5
- Mozilla Firefox Esr
- Mozilla Thunderbird — versions < 78.5
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required, Issue Tracking, Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2020-50/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2020-52/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2020-51/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2020-26956?
- CVE-2020-26956 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-2020-26956?
- Medium severity. CVSS v3 base score is 6.1 out of 10.