CVE-2023-54051: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54051 is a vulnerability in the Linux kernel's networking subsystem where a missing input validation check in virtio_net_hdr_to_skb() allows the gso_size field to be set to GSO_BY_FRAGS (0xffff), a magic value reserved for internal kernel use. This flaw can trigger a general protection fault (null pointer dereference) in skb_segment(), leading to a kernel crash. The vulnerability was formally published on December 24, 2025, and affects the Linux kernel. It carries an EPSS score of 0.024% (low), indicating limited exploitation probability at this time (Feedly, CVE.org).

The root cause is improper input validation (CWE-20) in the virtio_net_hdr_to_skb() function within the Linux kernel's network core. When a user-space process (or a virtio network device) supplies a gso_size value of 0xffff (GSO_BY_FRAGS), the kernel does not reject it, allowing this reserved sentinel value to propagate into skb_segment() at net/core/skbuff.c:4500. This causes a KASAN-detected null pointer dereference in the range [0x0000000000000070-0x0000000000000077], crashing the kernel with a general protection fault. The fix adds a check to explicitly reject GSO_BY_FRAGS as a user-supplied gso_size value (Feedly, CVE.org).

Successful exploitation results in a kernel crash (general protection fault), causing a denial of service on the affected system. An attacker with the ability to craft virtio network headers or interact with the relevant network interface could trigger this condition, bringing down the host or guest kernel. There is no evidence of confidentiality or integrity impact; the primary consequence is availability loss (Feedly).

• Logs: Kernel logs (dmesg or /var/log/kern.log) showing a general protection fault with the message KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077] and a stack trace referencing skb_segment+0x1a52/0x3ef0 net/core/skbuff.c:4500.
• Process: Unexpected kernel panics or system reboots on hosts running virtio network devices.
• Network: Anomalous virtio network header traffic with gso_size set to 0xffff (GSO_BY_FRAGS) originating from a guest VM or untrusted network source.

The Linux kernel maintainers have released patches across multiple stable branches addressing this issue. Affected users should update to a patched kernel version that includes the fix in virtio_net_hdr_to_skb() to reject GSO_BY_FRAGS as a user-supplied value. Relevant upstream commits include 0a593e8a9d24, 2e03a92b2411, 4c9bfadb4301, 210ff31342ad, and 578371ce0d7f on the stable kernel tree. Linux distribution vendors including SUSE have issued kernel security advisories (e.g., SUSE-2026-0281-1, SUSE-2026-20876-1) incorporating these fixes; users should apply the latest kernel updates from their distribution (Feedly, Linux Security SUSE).