CVE-2021-23953 Affecting thunderbird package, versions <1:78.7.0-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
1.05% (61st percentile)

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  • Snyk IDSNYK-ECHOLATEST-THUNDERBIRD-18319170
  • published26 Jul 2026
  • disclosed26 Feb 2021

Introduced: 26 Feb 2021

CVE-2021-23953  (opens in a new tab)

How to fix?

Upgrade Echo:latest thunderbird to version 1:78.7.0-1 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.

If a user clicked into a specifically crafted PDF, the PDF reader could be confused into leaking cross-origin information, when said information is served as chunked data. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.

CVSS Base Scores

version 3.1