All vulnerabilities

Servers and applications

CVE-2026-33555

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.

Severity
Medium 5.8
Published
13 Apr 2026
Last changed
18 Oct 2026
Added to UpHeron
21 Oct 2026
Fixed in
3.3.6
Sources
NVD

Affected software

SoftwareAffected versions
HAProxyServers and applications · cpe:a:haproxy:haproxy
  • From 2.6.0 before 3.3.6

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2026-33555
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-33555