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).

There is no public proof-of-concept exploit code and no evidence of in-the-wild exploitation as of the time of reporting. The vulnerability was discovered through automated fuzzing by syzbot/syzkaller. The EPSS score is approximately 0.018% (0.000180), indicating a very low probability of exploitation in the near term. The CVE is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. No threat actor attribution has been identified (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).