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 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.
Overview
- Severity
- High (CVSS 7.5)
- CVSS Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Exploit Status
- Not Exploited
- Patch Tuesday
- 2026-Oct
- Released
- 2026-10-25
- Last Updated
- 2026-10-26
- EPSS Score
- 0.81% (percentile: 56.6%)
Affected Products (1)
Other
Revision History
- 2026-10-25: Information published.
- 2026-10-26: Information published.