CVE-2026-110353: haproxy Unchecked Return Value

Vulnerability summary

CVE-2026-110353 is a high (CVSS 7.5) Unchecked Return Value vulnerability in haproxy.

Timeline

1. 22-10-2026
   PublishedVulnerability first disclosed.

Description

HAProxy 3.2 before 3.4.6 allows a remote unauthenticated attacker to cause a denial of service (worker-thread CPU exhaustion) via a truncated HTTP/2 PING frame. h2c_handle_ping in src/mux_h2.c does not check for a short read, unlike the other H2 frame handlers. Because the incomplete frame cannot be processed, its data is never consumed, and the H2 multiplexer tasklet is repeatedly woken by that pending data without making progress. The CPU spins until timeout http-request closes the connection, and an attacker opening many such connections can sustain high CPU usage.

• CWE-252Unchecked Return ValueThe product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.