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CVE-2024-42312 Siemens CVE debrief

CVE-2024-42312 is a Linux kernel vulnerability affecting the sysctl subsystem, specifically in how inode ownership fields (i_uid/i_gid) are initialized in /proc/sys inodes. The issue stems from incomplete initialization of these fields when set_ownership() callbacks skip setting them, potentially leading to use of uninitialized values. The vulnerability was resolved by ensuring i_uid/i_gid are always initialized in the sysfs core, with proper default values applied when ownership computation fails. Siemens has identified this as affecting the GNU/Linux subsystem of their SIMATIC S7-1500 TM MFP industrial control product. The vulnerability requires local access with low privileges and can result in high availability impact. No patch is currently available from Siemens; mitigation relies on access controls and trusted application practices.

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 systems with enabled GNU/Linux subsystems, particularly in industrial automation and critical infrastructure environments. Security teams responsible for embedded Linux systems in OT/ICS environments should prioritize access controls until patches become available.

Technical summary

This vulnerability exists in the Linux kernel's sysctl implementation where i_uid and i_gid fields of /proc/sys inodes may remain uninitialized when set_ownership() callbacks skip setting them. The root cause was incomplete handling in net_ctl_set_ownership() which failed to apply default ownership values when computation of better values failed. The resolution moves initialization to the sysfs core, ensuring these fields are always set before set_ownership() is called. The vulnerability is classified as CWE-20 (Improper Input Validation) and has a CVSS 3.1 score of 5.5 (MEDIUM) with local attack vector, low attack complexity, low privileges required, and high availability impact.

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 Siemens security advisories regarding patch availability for SSA-265688
  • Apply defense-in-depth strategies for industrial control systems per CISA guidance
  • Review and implement ICS-CERT recommended practices for securing embedded Linux subsystems

Evidence notes

The vulnerability description indicates this is a kernel-level fix for uninitialized inode ownership fields in the sysctl/proc_sysctl subsystem. The fix ensures i_uid/i_gid are always initialized in the sysfs core, addressing a gap where net_ctl_set_ownership() failed to apply default values when ownership computation failed. Siemens has confirmed this affects their SIMATIC S7-1500 TM MFP product's GNU/Linux subsystem.

Official resources

2024-04-09