Improper Handling of Length Parameter Inconsistency The advisory has been revoked - it doesn't affect any version of package haproxy (opens in a new tab)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-RHEL9-HAPROXY-16069598
- published15 Apr 2026
- disclosed13 Apr 2026
Introduced: 13 Apr 2026
CVE-2026-33555 (opens in a new tab)Amendment
The Red Hat security team deemed this advisory irrelevant for RHEL:9.
NVD Description
Note: Versions mentioned in the description apply only to the upstream haproxy package and not the haproxy package as distributed by RHEL.
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
References
- https://access.redhat.com/security/cve/CVE-2026-33555
- https://github.com/haproxy/haproxy/commit/05a295441c621089ffa4318daf0dbca2dd756a84
- https://www.haproxy.com/documentation/haproxy-aloha/changelog/
- https://www.haproxy.org
- https://www.mail-archive.com/haproxy@formilux.org/msg46752.html
- https://r3verii.github.io/cve/2026/04/14/haproxy-h3-standalone-fin-smuggling.html