CVE-2020-26951

6.1 mediumEPSS 1.1%

Medium (6.1) in mozilla. EPSS 1.1% chance of exploitation in the next 30 days.

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.

Severity

CVSS 3.1

6.1 medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS: 1.1% chance of exploitation in the next 30 days; higher than 64% of CVEs (scores of 2026-10-31)
CWE: CWE-79
Published: 2020-12-09
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox
mozilla:firefox_esr
mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1667113
https://www.mozilla.org/security/advisories/mfsa2020-50/
https://www.mozilla.org/security/advisories/mfsa2020-51/
https://www.mozilla.org/security/advisories/mfsa2020-52/
https://bugzilla.mozilla.org/show_bug.cgi?id=1667113

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