CVE-2022-50405: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-50405 is a NULL pointer dereference vulnerability in the Linux kernel's VXLAN (Virtual Extensible LAN) tunnel networking subsystem. The flaw arises from a race condition when a VXLAN device is deleted while packets are simultaneously being received, potentially causing the socket (sock) to be released after vxlan_sock is retrieved from sk_user_data, leading to a kernel crash in vxlan_ecn_decapsulate() or vxlan_get_sk_family(). It was published on September 18, 2025, and affects multiple Linux kernel stable branches. The vulnerability carries a CVSS v3.1 base score of 5.5 (Medium) (Feedly).

The root cause is classified as CWE-476 (NULL Pointer Dereference), triggered by a time-of-check/time-of-use (TOCTOU) race condition in the net/tunnel subsystem. When a VXLAN device is torn down concurrently with packet reception, the socket referenced via sk_user_data can be freed before all readers have finished using it; subsequent calls to vxlan_ecn_decapsulate() or vxlan_get_sk_family() then dereference a NULL or freed pointer, causing a kernel oops. The attack vector is local (AV:L), requires low privileges (PR:L), and no user interaction, meaning a local user with sufficient permissions to manipulate network interfaces or trigger packet reception during device deletion can trigger the crash. The fix involves ensuring all sk_user_data readers complete before the socket is released (Feedly, Kernel Patch).

Successful exploitation causes a kernel NULL pointer dereference, resulting in a system crash (kernel panic/oops) and denial of service — the primary impact is high availability loss with no confidentiality or integrity impact. The vulnerability affects any Linux system using VXLAN networking (common in virtualized and containerized environments), and a crash could disrupt all workloads on the affected host. There is no evidence of data exfiltration or privilege escalation as a direct consequence (Feedly).

No public proof-of-concept exploit code or in-the-wild exploitation has been reported for CVE-2022-50405. The EPSS score is approximately 0.033% (0.000330), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires local access and the ability to delete a VXLAN device while network traffic is being processed, limiting the practical attack surface (Feedly).

The Linux kernel maintainers have released patches across multiple stable branches. Affected users should upgrade to the following fixed versions or later: 4.9.337, 4.14.303, 4.19.270, 5.4.229, 5.10.163, 5.15.86, 6.0.16, or 6.1.2. Nine separate stable-branch commits have been issued to address this race condition. Linux distribution vendors (e.g., Red Hat, Ubuntu, SUSE) are expected to backport these fixes into their respective kernel packages; users should apply the latest kernel updates from their distribution. As a temporary workaround where patching is not immediately possible, avoiding concurrent VXLAN device deletion during active traffic can reduce exposure (Feedly, Kernel Patch).