Cross-site Scripting (XSS) Affecting thunderbird package, versions <1:78.5.0-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
1.04% (60th percentile)

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  • Snyk IDSNYK-ECHOLATEST-THUNDERBIRD-18319153
  • published26 Jul 2026
  • disclosed9 Dec 2020

Introduced: 9 Dec 2020

CVE-2020-26951  (opens in a new tab)
CWE-79  (opens in a new tab)

How to fix?

Upgrade Echo:latest thunderbird to version 1:78.5.0-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream thunderbird package and not the thunderbird package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1