PatchSiren cyber security CVE debrief

CVE-2024-33621 Linux CVE debrief

A vulnerability in the Linux kernel's IPvlan network driver could allow a local, privileged attacker to cause a denial of service (DoS) condition. The flaw exists in the `ipvlan_process_v4_outbound` and `ipvlan_process_v6_outbound` functions, which improperly use `skb->sk` (socket buffer socket pointer) during packet processing. This can lead to a NULL pointer dereference or use-after-free condition, resulting in a system crash. The vulnerability affects Siemens SIMATIC S7-1500 TM MFP devices that utilize the GNU/Linux subsystem. Exploitation requires local access with high privileges to the interactive shell of the GNU/Linux subsystem. No patch is currently available from the vendor.

Vendor: Linux
Product: SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS: MEDIUM 4.4
CISA KEV: Not listed in stored evidence
Original CVE published: 2024-04-09
Original CVE updated: 2026-05-14
Advisory published: 2024-04-09
Advisory updated: 2026-05-14

Who should care

Organizations operating Siemens SIMATIC S7-1500 TM MFP industrial controllers with the GNU/Linux subsystem enabled. OT security teams, industrial network administrators, and asset owners in manufacturing, process control, and critical infrastructure sectors should prioritize access controls and monitoring for this unpatched vulnerability.

Technical summary

The vulnerability resides in the Linux kernel's IPvlan (IP virtual LAN) driver, specifically in the outbound packet processing functions for IPv4 and IPv6. The functions `ipvlan_process_v4_outbound` and `ipvlan_process_v6_outbound` incorrectly reference `skb->sk`, the socket pointer in the socket buffer structure. Under certain conditions, this pointer may be NULL or invalid, leading to a NULL pointer dereference or use-after-free when the driver attempts to access socket-related data during packet transmission. This results in a kernel oops or panic, causing system availability impact. The vulnerability is classified as CWE-1287 (Improper Validation of Specified Type of Input).

Defensive priority

medium

Recommended defensive actions

Restrict access to the interactive shell of the GNU/Linux subsystem to trusted personnel only
Only build and run applications from trusted sources
Monitor for anomalous system crashes or kernel panics on affected devices
Apply vendor patches when they become available
Review network segmentation to limit exposure of affected industrial control systems

Evidence notes

Vulnerability disclosed in Linux kernel ipvlan driver. Affects Siemens SIMATIC S7-1500 TM MFP GNU/Linux subsystem. CVSS 3.1 score 4.4 (MEDIUM). No fix currently available per vendor advisory.

Official resources

2024-04-09