Protection Mechanism Failure Affecting Firefox-ESR package, versions [,140.13)
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-UNMANAGED-FIREFOXESR-18302667
- published25 Jul 2026
- disclosed21 Jul 2026
- creditUnknown
Introduced: 21 Jul 2026
CVE-2026-16377 (opens in a new tab)How to fix?
Upgrade Firefox-ESR to version 140.13 or higher.
Overview
Affected versions of this package are vulnerable to Protection Mechanism Failure in the PDF Viewer component. An attacker can bypass implemented security mitigations by exploiting weaknesses in the mitigation logic.