Client-Side Enforcement of Server-Side Security Affecting Firefox-ESR package, versions [,115.33.0)[116.0,140.8.0)
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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- published25 Feb 2026
- disclosed24 Feb 2026
- creditUnknown
Introduced: 24 Feb 2026
CVE-2026-2775 (opens in a new tab)How to fix?
Upgrade Firefox-ESR to version 115.33.0, 140.8.0 or higher.
Overview
Affected versions of this package are vulnerable to Client-Side Enforcement of Server-Side Security through the HTML parsing process. An attacker can bypass implemented mitigations by crafting malicious HTML content that is processed by the HTML Parser component.