RHSA-2026:55803HighCVSS 7.5

Red Hat Security Advisory: haproxy security update

Published
August 17, 2026
Last Modified
August 17, 2026

🔗 CVE IDs covered (2)

CVE-2026-55204 →CVE-2026-55203 →

📋 Description

CVE-2026-55203 — haproxy: HAProxy: Response smuggling due to integer overflow in FastCGI record length handling CVE-2026-55204 — haproxy: HAProxy: Denial of Service via HPACK dynamic table insertions

🎯 Affected products14

  • Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-0:2.4.22-4.el9_6.3.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-0:2.4.22-4.el9_6.3.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-0:2.4.22-4.el9_6.3.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-0:2.4.22-4.el9_6.3.src as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-0:2.4.22-4.el9_6.3.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debuginfo-0:2.4.22-4.el9_6.3.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debuginfo-0:2.4.22-4.el9_6.3.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debuginfo-0:2.4.22-4.el9_6.3.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debuginfo-0:2.4.22-4.el9_6.3.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debugsource-0:2.4.22-4.el9_6.3.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debugsource-0:2.4.22-4.el9_6.3.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debugsource-0:2.4.22-4.el9_6.3.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)
  • haproxy-debugsource-0:2.4.22-4.el9_6.3.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v.9.6)

✅ Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Workaround: To mitigate this issue, restrict access to HAProxy instances that utilize FastCGI to trusted FastCGI backends only. If FastCGI is not required, consider disabling its use in HAProxy configurations to eliminate the attack vector. Ensure that all FastCGI backends are secured and not susceptible to compromise. If the HAProxy service is reloaded or restarted after configuration changes, ensure proper validation of the new configuration. Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

🔗 References (5)