CVE-2025-6433 Affecting firefox-esr package, versions <140-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.24% (16th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-FIREFOXESR-17764216
  • published1 Jul 2026
  • disclosed24 Jun 2025

Introduced: 24 Jun 2025

CVE-2025-6433  (opens in a new tab)

How to fix?

Upgrade Chainguard firefox-esr to version 140-r0 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 Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

If a user visited a webpage with an invalid TLS certificate, and granted an exception, the webpage was able to provide a WebAuthn challenge that the user would be prompted to complete. This is in violation of the WebAuthN spec which requires "a secure transport established without errors". This vulnerability was fixed in Firefox 140 and Thunderbird 140.

CVSS Base Scores

version 3.1