CVE-2025-5020 Affecting firefox-esr package, versions <139-r0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-CHAINGUARDLATEST-FIREFOXESR-17765196
- published1 Jul 2026
- disclosed21 May 2025
Introduced: 21 May 2025
CVE-2025-5020 (opens in a new tab)How to fix?
Upgrade Chainguard firefox-esr to version 139-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.
Opening maliciously-crafted URLs in Firefox from other apps such as Safari could have allowed attackers to spoof website addresses if the URLs utilized non-HTTP schemes used internally by the Firefox iOS client. This vulnerability was fixed in Firefox for iOS 139.