CVE-2026-23064: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-23064 is a NULL pointer dereference vulnerability (CWE-476) in the Linux kernel's network traffic control subsystem, specifically in the net/sched/act_ife module. The flaw exists because tcf_ife_encode() does not validate that ife_encode() returns a non-NULL pointer before passing it to ife_tlv_meta_encode(), which can trigger a kernel general protection fault. It affects Linux kernel versions from 4.11 through multiple stable branches, with fixed versions including 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8, and 6.19-rc7. The vulnerability was published on February 4, 2026, and carries a CVSS v3.1 base score of 5.5 (Medium) (Feedly, kernel.org patches).

The root cause is a missing NULL return-value check in tcf_ife_encode() within net/sched/act_ife.c (CWE-476: NULL Pointer Dereference). When ife_encode() returns NULL — for example due to memory allocation failure — the code proceeds to pass this NULL pointer to ife_tlv_meta_encode() at net/ife/ife.c:166, which then attempts to dereference it, causing a kernel oops (general protection fault at address range 0x0000000000000000–0x0000000000000007). The bug was discovered and reported by syzbot (syzkaller fuzzer), with the crash trace showing the call path: ife_encode_meta_u32 → tcf_ife_encode → tcf_ife_act → tcf_action_exec → packet classification and qdisc enqueue routines. Exploitation requires only low privileges and no user interaction, as the vulnerable code path is reachable via crafted network packets processed through a configured act_ife traffic control action (Feedly).

Successful exploitation causes a kernel panic (general protection fault), resulting in a denial of service — the affected system crashes or becomes unresponsive. The impact is limited to availability; there is no confidentiality or integrity impact identified. Because the crash occurs in kernel context during packet processing, any system with the act_ife traffic control action configured and reachable by a low-privileged local attacker is at risk (Feedly).

Apply the available kernel patches to upgrade to a fixed version. Patched stable kernel releases include: 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8, and 6.19-rc7 or later. Patches are available at the Linux kernel stable git repository. As a temporary workaround if patching is not immediately possible, restrict or remove act_ife traffic control configurations and limit local access to network configuration interfaces (e.g., via tc). Ubuntu security notices (USN-8162-1, USN-8180-x series, USN-8186-1, USN-8188-1, USN-8275-1, USN-8278-x, USN-8289-x, USN-8296-x, USN-8297-1, USN-8393-1) and SUSE advisories (SUSE-2026-0962-1) address this CVE for their respective distributions (Feedly, kernel.org patches, Ubuntu USN-8180-1).