Is CVE-2026-33555 actively exploited?

No active exploitation of CVE-2026-33555 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-33555 be exploited remotely?

Yes. CVE-2026-33555 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-33555?

CVE-2026-33555 has a CVSS score of 4.0 (MEDIUM).

HOME VULNERABILITIESCVE-2026-33555

MEDIUM

CVE-2026-33555

CWE-130Published: April 13, 2026· Updated: Apr 17, 2026

4.0

CVSS v3.1

EPSS:0.01%probability of exploitation in 30 daysPercentile:0.8th

Official Description

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.

NVD Source

Technical Analysis

CVE-2026-33555 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.