PatchSiren cyber security CVE debrief

CVE-2024-36008 Siemens CVE debrief

A NULL pointer dereference vulnerability exists in the Linux kernel's IPv4 routing subsystem. The flaw occurs in ip_route_use_hint() when the function fails to validate that the idev (in-device) pointer is non-NULL before use. This can lead to a kernel crash via NULL dereference in fib_validate_source(). The vulnerability was discovered by syzbot and affects current kernel trees. Siemens has identified this as affecting the GNU/Linux subsystem of SIMATIC S7-1500 TM MFP industrial control devices. No patch is currently available from the vendor.

Vendor: Siemens
Product: SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
CVSS: MEDIUM 5.5
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 control systems with the GNU/Linux subsystem enabled; OT security teams managing Linux-based embedded systems in industrial environments; kernel maintainers and Linux distribution security teams tracking upstream fixes

Technical summary

The vulnerability is a NULL pointer dereference in the Linux kernel's IPv4 routing implementation. The ip_route_use_hint() function in net/ipv4/route.c fails to check whether the idev (in-device structure) is NULL before dereferencing it. This leads to a crash in fib_validate_source() when processing certain network routing hints. The flaw was found through automated fuzzing (syzbot) and exists in current kernel versions. On affected Siemens SIMATIC S7-1500 TM MFP devices, this could allow an authenticated local user to cause a denial of service (system crash) through the GNU/Linux subsystem.

Defensive priority

medium

Recommended defensive actions

Restrict interactive shell access to the GNU/Linux subsystem to trusted personnel only
Only build and execute applications from trusted sources
Monitor for kernel crashes or unexpected reboots on affected devices
Apply vendor patches when released per Siemens security advisory SSA-265688
Segment affected industrial control systems from untrusted networks

Evidence notes

The vulnerability description indicates a NULL pointer dereference in the Linux kernel's IPv4 routing code, specifically in ip_route_use_hint() leading to fib_validate_source(). The syzbot fuzzer triggered this crash. Siemens has confirmed this affects their SIMATIC S7-1500 TM MFP product's GNU/Linux subsystem. The CVSS 3.1 vector indicates local attack vector with low attack complexity, requiring low privileges and resulting in high availability impact.

Official resources

2024-04-09