RHSA-2026:61245HighCVSS 9.1

Red Hat Security Advisory: osbuild-composer security update

Published
August 31, 2026
Last Modified
September 18, 2026

🔗 CVE IDs covered (2)

CVE-2026-33186 →CVE-2026-39821 →

📋 Description

CVE-2026-33186 — google.golang.org/grpc/grpc-go: google.golang.org/grpc/authz: gRPC-Go: Authorization bypass due to improper HTTP/2 path validation CVE-2026-39821 — golang.org/x/net/idna: golang: net/http: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing

🎯 Affected products38

  • Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-0:76.1-7.el9_2.aarch64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-0:76.1-7.el9_2.ppc64le as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-0:76.1-7.el9_2.s390x as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-0:76.1-7.el9_2.src as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-0:76.1-7.el9_2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-0:76.1-7.el9_2.aarch64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-0:76.1-7.el9_2.ppc64le as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-0:76.1-7.el9_2.s390x as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-0:76.1-7.el9_2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-debuginfo-0:76.1-7.el9_2.aarch64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-debuginfo-0:76.1-7.el9_2.ppc64le as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-debuginfo-0:76.1-7.el9_2.s390x as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-core-debuginfo-0:76.1-7.el9_2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debuginfo-0:76.1-7.el9_2.aarch64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debuginfo-0:76.1-7.el9_2.ppc64le as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debuginfo-0:76.1-7.el9_2.s390x as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debuginfo-0:76.1-7.el9_2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debugsource-0:76.1-7.el9_2.aarch64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debugsource-0:76.1-7.el9_2.ppc64le as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debugsource-0:76.1-7.el9_2.s390x as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-debugsource-0:76.1-7.el9_2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-dnf-json-0:76.1-7.el9_2.aarch64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-dnf-json-0:76.1-7.el9_2.ppc64le as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-dnf-json-0:76.1-7.el9_2.s390x as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-dnf-json-0:76.1-7.el9_2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-tests-debuginfo-0:76.1-7.el9_2.aarch64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-tests-debuginfo-0:76.1-7.el9_2.ppc64le as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-tests-debuginfo-0:76.1-7.el9_2.s390x as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • osbuild-composer-tests-debuginfo-0:76.1-7.el9_2.x86_64 as a component of Red Hat Enterprise Linux AppStream E4S (v.9.2)
  • +8 more not shown

✅ 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, implement infrastructure-level normalization to ensure all incoming HTTP/2 `:path` headers are properly formatted with a leading slash before reaching the gRPC-Go server. This can be achieved by configuring a reverse proxy or API gateway to validate and normalize the `:path` header. Ensure that any such intermediary is properly configured and restarted to apply the changes, which may temporarily impact service availability. Workaround: Upgrade to a fixed golang.org/x/net release that includes the idna correction, via updated golang or dependent package rebuilds.

🔗 References (5)