Improper Handling of Length Parameter Inconsistency Affecting haproxy package, versions [2.6-dev0,3.3.6)
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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- published22 Apr 2026
- disclosed13 Apr 2026
- creditUnknown
Introduced: 13 Apr 2026
CVE-2026-33555 (opens in a new tab)How to fix?
Upgrade haproxy to version 3.3.6 or higher.
Overview
Affected versions of this package are vulnerable to Improper Handling of Length Parameter Inconsistency in the HTTP/3 parser when it fails to verify that the received body length matches the previously announced content-length if the stream is closed via a frame with an empty payload. An attacker can cause desynchronization with the backend server by sending specially crafted HTTP/3 requests.