SB20260721149 - Multiple vulnerabilities in Red Hat OpenShift Container Platform 4.21
Published: July 21, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2026-46242)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause memory corruption.
The vulnerability exists due to a use-after-free in ep_remove() in fs/eventpoll.c when removing epoll file references during a race with file release handling. A local user can trigger a race condition to cause memory corruption.
The issue involves the epoll-watches-epoll case and a concurrent __fput() path that can lead to operations on freed structures.
2) Double free (CVE-ID: CVE-2026-46316)
CWE-ID: CWE-415 - Double Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a double free in vgic_its_invalidate_cache() in the KVM arm64 vgic-its translation cache when invalidating cache entries concurrently. A local user can trigger concurrent cache invalidation paths to cause a denial of service.
The issue occurs because multiple contexts can drain the same cache at the same time, allowing an entry to be freed while an ITE still maps it.
3) Use-after-free (CVE-ID: CVE-2026-53359)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in the KVM x86 shadow paging logic when changing a PDE mapping from outside the guest and deleting a memslot. A local user can trigger stale rmap entries and subsequent dereference of a freed sptep to cause a denial of service.
The issue occurs when a modified PDE points to a non-leaf page, causing a role mismatch between reused shadow pages for large 2MB mappings and new 4KB mappings.
Remediation
Install update from vendor's website.