CVE-2022-50253: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-50253 is a denial-of-service vulnerability in the Linux kernel's BPF (Berkeley Packet Filter) subsystem, specifically in network packet redirection to tunneling devices. The flaw allows a local attacker with low privileges to trigger a kernel warning and cause unexpected system behavior by inducing a zero-length socket buffer (skb->len == 0) during packet transmission via bpf_clone_redirect. It affects Linux kernel versions from 4.14 up to (but not including) 4.14.303, 4.15–4.19.270, 4.20–5.4.229, 5.5–5.10.163, 5.11–5.15.86, 5.16–6.0.16, and 6.1–6.1.2. The vulnerability was publicly disclosed on September 15, 2025, and carries a CVSS v3.1 base score of 5.5 (Medium) (Red Hat Advisory, Red Hat Bugzilla).

The root cause is an improper input validation / missing bounds check (CWE-20) in the BPF packet redirection path within net/core/filter.c. When a BPF program uses bpf_clone_redirect to redirect a packet to a tunneling device, the kernel calls __skb_pull to strip the L2 (Ethernet) header before transmission. If the packet is exactly ETH_HLEN bytes long, this pull operation reduces skb->len to zero, violating the invariant checked by skb_assert_len in __dev_queue_xmit. The fix adds an explicit length check after the __skb_pull call to prevent zero-length packets from being forwarded. The vulnerability was originally discovered via syzkaller fuzzing (Red Hat Bugzilla, Red Hat Advisory).

Successful exploitation results in a kernel WARNING being triggered in __dev_queue_xmit, which can cause denial of service through unexpected kernel behavior or system instability. The impact is limited to availability — there is no confidentiality or integrity impact. Because exploitation requires local access with low privileges (e.g., the ability to load and run BPF programs), the blast radius is confined to the affected host and does not directly enable lateral movement or data exfiltration (Red Hat Advisory, Red Hat Bugzilla).

The primary remediation is to update the Linux kernel to a patched version: 4.14.303, 4.19.270, 5.4.229, 5.10.163, 5.15.86, 6.0.16, or 6.1.2 (or later). Patches are available via the upstream stable kernel tree. For systems that cannot be immediately patched, administrators should restrict local user access to BPF program loading (e.g., by setting kernel.unprivileged_bpf_disabled=1 via sysctl) and use kernel security modules such as SELinux or AppArmor to limit BPF syscall access. SUSE has also released kernel security updates addressing this CVE (Red Hat Advisory, Linux Security SUSE).

Red Hat has tracked this vulnerability at low severity/priority in their Bugzilla system, reflecting the limited exploitability and local-only attack vector. SUSE has issued multiple kernel security updates (SUSE-SU-2025:4393-1, SUSE-SU-2025:4422-1, SUSE-SU-2025:4505-1, and others) addressing this CVE. No notable researcher commentary or significant social media discussion has been observed beyond standard vendor advisory channels (Red Hat Bugzilla, Linux Security SUSE).