RHSA-2026:27856 - Security Advisory

Topic

An update for osbuild-composer is now available for Red Hat Enterprise Linux 10.0 Extended Update Support.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

A service for building customized OS artifacts, such as VM images and OSTree commits, that uses osbuild under the hood. Besides building images for local usage, it can also upload images directly to cloud. It is compatible with composer-cli and cockpit-composer clients.

Security Fix(es):

• google.golang.org/grpc/grpc-go: google.golang.org/grpc/authz: gRPC-Go: Authorization bypass due to improper HTTP/2 path validation (CVE-2026-33186)
• github.com/go-jose/go-jose/v3: github.com/go-jose/go-jose/v4: Go JOSE: Denial of Service via crafted JSON Web Encryption (JWE) object (CVE-2026-34986)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Update Support 10.0 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 10.0 s390x
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 10.0 ppc64le
• Red Hat Enterprise Linux for ARM 64 - Extended Update Support 10.0 aarch64
• Red Hat Enterprise Linux for ARM 64 - 4 years of updates 10.0 aarch64
• Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 10.0 s390x
• Red Hat Enterprise Linux for Power, little endian - 4 years of support 10.0 ppc64le
• Red Hat Enterprise Linux for x86_64 - 4 years of updates 10.0 x86_64

Fixes

• BZ - 2449833 - 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
• BZ - 2455470 - CVE-2026-34986 github.com/go-jose/go-jose/v3: github.com/go-jose/go-jose/v4: Go JOSE: Denial of Service via crafted JSON Web Encryption (JWE) object

CVEs

• CVE-2026-33186
• CVE-2026-34986

References

• https://access.redhat.com/security/updates/classification/#important