CVE-2026-110354 HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via a
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-110354?
CVE-2026-110354 is a high-severity vulnerability in HAProxy, published on 22 Oct 2026.
Official description
HAProxy 3 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (persistent worker-thread CPU exhaustion) via an HTTP/1.1 chunked request. Although the H1 multiplexer drains the request before closing the stream, the parser repeatedly re-processes the same bytes without making progress. The affected thread stays busy at 100% CPU after timeouts expire and after the client disconnects, and repeated requests can consume all worker threads until the process is restarted.
Weakness: CWE-835
Which versions are affected by CVE-2026-110354?
How do I fix CVE-2026-110354?
Upgrade to a fixed version.
Is CVE-2026-110354 being exploited?
There is no known exploitation of CVE-2026-110354 in the wild and no public exploit code.
Sources
Also known as AZL-111017, DEBIAN-CVE-2026-110354, GHSA-vqpp-w68q-p3f5, UBUNTU-CVE-2026-110354.