RHSA-2026:50538HighCVSS 7.5

Red Hat Security Advisory: mod_http2 security update

Published
August 5, 2026
Last Modified
August 18, 2026

🔗 CVE IDs covered (4)

CVE-2025-53020 →CVE-2026-43951 →CVE-2026-48913 →CVE-2026-49975 →

📋 Description

CVE-2025-53020 — mod_http2: Apache HTTP Server: HTTP/2 DoS by Memory Increase CVE-2026-43951 — httpd: Apache HTTP Server: Out-of-bounds Read in mod_headers and mod_mime CVE-2026-48913 — httpd: mod_http2: Apache HTTP Server mod_http2: Use After Free vulnerability allows arbitrary code execution or denial of service. CVE-2026-49975 — httpd: httpd: HTTP/2 Remote Denial of Service via compression bomb and Slowloris-style attack

🎯 Affected products14

  • Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-0:2.0.29-2.el10_0.2.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-0:2.0.29-2.el10_0.2.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-0:2.0.29-2.el10_0.2.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-0:2.0.29-2.el10_0.2.src as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-0:2.0.29-2.el10_0.2.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debuginfo-0:2.0.29-2.el10_0.2.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debuginfo-0:2.0.29-2.el10_0.2.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debuginfo-0:2.0.29-2.el10_0.2.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debuginfo-0:2.0.29-2.el10_0.2.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debugsource-0:2.0.29-2.el10_0.2.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debugsource-0:2.0.29-2.el10_0.2.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debugsource-0:2.0.29-2.el10_0.2.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • mod_http2-debugsource-0:2.0.29-2.el10_0.2.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)

✅ 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: The attack surface can be reduced by disabling HTTP/2 support in Apache. Follow the guidance in Red Hat KCS article to: - Remove h2 and h2c from the Protocols directive - Disable mod_http2 and mod_proxy_http2 modules (if not required) https://access.redhat.com/node/7056356 Workaround: - Those who do not require multi-language response headers can remove or disable the `mod_headers` and `mod_mime` modules, or remove Content-Language directives from their configuration. - Systems not using these modules in combination are not affected. Workaround: To mitigate this issue, disable the `mod_http2` module if HTTP/2 protocol support is not required. This can be achieved by commenting out or removing the `LoadModule http2_module modules/mod_http2.so` line in the Apache HTTP Server configuration file (e.g., `/etc/httpd/conf.modules.d/00-base.conf` or similar). After modifying the configuration, the httpd service must be restarted for the changes to take effect. This action may impact services relying on HTTP/2. Workaround: See the security bulletin for a detailed mitigation procedure.

🔗 References (7)