HAProxy vulnerabilities
Summary
It was discovered that HAProxy incorrectly handled the FCGI demultiplexer record length field. A remote attacker could possibly use this issue to cause incorrect request routing, response smuggling, or other memory safety issues. (CVE-2026-55203) It was discovered that HAProxy failed to validate the return value of the HPACK dynamic table defragmentation function when memory was exhausted. A remote attacker could possibly use this issue to cause HAProxy to crash, resulting in a denial of service. (CVE-2026-55204) Affected Ubuntu releases: 26.04, 25.10, 24.04, 22.04. CVEs: CVE-2026-55204, CVE-2026-55203.
- Ubuntu 26.04
- Ubuntu 25.10
- Ubuntu 24.04
- Ubuntu 22.04
Official advisory · medium-confidence parse· fetched 4 hours ago·verify at source
Mitigation checklist
- Apply available updates: `sudo apt update && sudo apt upgrade` (a standard system update installs the fix).
Official advisory · medium-confidence parse· fetched 4 hours ago·verify at source
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