SB2026081111 - Red Hat Enterprise Linux 9 update for kernel
Published: August 11, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2026-31530)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 6.8 [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]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to use-after-free in cxl_detach_ep() when handling concurrent endpoint detach operations and switch port removal. A local user can trigger concurrent device detach and port unregistration to cause a denial of service.
This issue is reproducible when reloading cxl_acpi in QEMU with CXL devices present.
2) Improper privilege management (CVE-ID: CVE-2025-54518)
CWE-ID: CWE-269 - Improper Privilege Management
CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to escalate privileges.
The vulnerability exists due to improper privilege management in x86 CPU opcode cache handling when executing code on affected AMD Fam17h CPUs. A local user can execute code to escalate privileges.
The issue can permit escalation across privilege boundaries including userspace to kernel and guest to host, and only AMD Fam17h CPUs based on the Zen2 microarchitecture are believed to be affected.
3) Improper Initialization (CVE-ID: CVE-2026-64368)
CWE-ID: CWE-665 - Improper Initialization
CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to disclose sensitive information.
The vulnerability exists due to improper initialization in slab allocation handling in mm/slub.c when allocating kmalloc objects with zeroing enabled. A local user can trigger a memory allocation pattern that leaves part of the allocated object uninitialized to disclose sensitive information.
The issue occurs when requested-size tracking is not enabled while red zoning alone is enabled, which can break krealloc() __GFP_ZERO expectations.
4) Improper input validation (CVE-ID: CVE-2026-64531)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 6.8 [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]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper handling of oversized nested action attributes in openvswitch flow action construction when processing user-supplied openvswitch nested action attributes. A local user can supply specially crafted nested CLONE or CT actions to cause a denial of service.
The issue occurs because a generated nested action attribute can be closed with a truncated nla_len, causing later dump or teardown operations to walk a structurally different action stream than the one that was validated.
Remediation
Install update from vendor's website.