CVE-2026-9309 The advisory has been revoked - it doesn't affect any version of package firefox-esr (opens in a new tab)
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-17764710
- published1 Jul 2026
- disclosed1 Jun 2026
Introduced: 1 Jun 2026
CVE-2026-9309 (opens in a new tab)Amendment
The Chainguard security team deemed this advisory irrelevant for Chainguard:latest.
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.
Firefox for iOS Reader View did not properly escape HTML tags in JSON-LD metadata. A malicious page could inject markup that changed Reader View behavior and leaked sensitive URL parameters. These parameters could then be used to access internal pages, potentially resulting in arbitrary JavaScript execution in an internal origin. This vulnerability was fixed in Firefox for iOS 151.2.