CVE-2025-5270 Affecting firefox package, versions <139-r0


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.25% (17th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-FIREFOX-17763824
  • published1 Jul 2026
  • disclosed27 May 2025

Introduced: 27 May 2025

CVE-2025-5270  (opens in a new tab)

How to fix?

Upgrade Chainguard firefox to version 139-r0 or higher.

NVD Description

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

In certain cases, SNI could have been sent unencrypted even when encrypted DNS was enabled. This vulnerability was fixed in Firefox 139 and Thunderbird 139.

CVSS Base Scores

version 3.1