CVE-2026-33555
low-risk
Published 2026-04-13
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.
Do I need to act?
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
4
CVSS 4.0/10
Medium
NETWORK
/ HIGH complexity
18
/ 100
low-risk
Severity
13/34 · Low
Exploitability
0/34 · Minimal
Exposure
5/34 · Minimal