Cross-site Scripting (XSS) Affecting firefox-esr package, versions <68.2.0esr-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.99% (58th percentile)

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  • Snyk IDSNYK-ECHOLATEST-FIREFOXESR-18169202
  • published22 Jul 2026
  • disclosed8 Jan 2020

Introduced: 8 Jan 2020

CVE-2019-11763  (opens in a new tab)
CWE-79  (opens in a new tab)

How to fix?

Upgrade Echo:latest firefox-esr to version 68.2.0esr-1 or higher.

NVD Description

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

Failure to correctly handle null bytes when processing HTML entities resulted in Firefox incorrectly parsing these entities. This could have led to HTML comment text being treated as HTML which could have led to XSS in a web application under certain conditions. It could have also led to HTML entities being masked from filters - enabling the use of entities to mask the actual characters of interest from filters. This vulnerability affects Firefox < 70, Thunderbird < 68.2, and Firefox ESR < 68.2.

CVSS Base Scores

version 3.1