SB20260731188 - Red Hat Enterprise Linux 9 update for kernel
Published: July 31, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 vulnerabilities.
1) Use-after-free (CVE-ID: CVE-2026-52923)
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 ipc_idr_alloc() in the checkpoint/restore SysV IPC allocation path when processing a request for the next SysV IPC id. A local user can request allocation beyond the valid IPC id range to cause a denial of service.
A subsequent walk of /proc/sysvipc/shm can dereference freed memory through a stale IDR entry.
2) Double free (CVE-ID: CVE-2026-52993)
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 double free in tipc_buf_append() when validating a reassembled skb after tipc_msg_validate() reallocates it. A local user can trigger the error-handling path with a crafted TIPC message to cause a denial of service.
3) Use-after-free (CVE-ID: CVE-2026-64530)
CWE-ID: CWE-416 - Use After Free
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in tcf_qevent_handle in net/sched/cls_api.c when handling TC_ACT_CONSUMED during qevent processing of fragmented traffic. A local user can send specially crafted fragmented network traffic to trigger use of an skb after ownership has been transferred and cause a denial of service.
Exploitation requires RED qdisc qevents together with ct defragmentation and traffic that produces out-of-order fragments.
Remediation
Install update from vendor's website.