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PatchSiren cyber security CVE debrief

CVE-2024-39480 Siemens CVE debrief

A buffer overflow vulnerability exists in the Linux kernel's kdb (kernel debugger) component, specifically during tab-completion of symbols. The flaw stems from incorrect use of strncpy() where the size of the source buffer is passed instead of the destination buffer. This can result in writing past the end of the command buffer when the cursor is positioned in the middle of a full buffer. The vulnerability has been resolved by replacing strncpy() calls with memmove()/memcpy() plus explicit boundary checks. Siemens has identified this as affecting SINEC OS and related industrial network infrastructure products.

Vendor
Siemens
Product
RUGGEDCOM RST2428P (6GK6242-6PA00)
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2025-08-12
Original CVE updated
2026-02-25
Advisory published
2025-08-12
Advisory updated
2026-02-25

Who should care

Organizations operating Siemens industrial network infrastructure including SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family and SCALANCE XCM-/XRM-/XCH-/XRH-300 family switches, as well as any Linux-based systems with kdb kernel debugging enabled. System administrators responsible for OT/ICS security and patch management should prioritize this update.

Technical summary

The kdb (kernel debugger) component in the Linux kernel contains a buffer overflow vulnerability triggered during symbol tab-completion. The root cause is an incorrect strncpy() call where the source buffer size is used as the length parameter instead of the destination buffer size. When the command buffer is full and the cursor (cp) is positioned mid-buffer, this error permits writes beyond the buffer boundary. The resolution replaces strncpy() with memmove()/memcpy() operations accompanied by explicit boundary validation to ensure sufficient space exists before character manipulation. This vulnerability is classified as HIGH severity (CVSS 7.8) with local attack vector, low attack complexity, and low privileges required, enabling high impact to confidentiality, integrity, and availability.

Defensive priority

HIGH

Recommended defensive actions

  • Apply vendor-provided updates to V3.1 or later for affected Siemens SINEC OS and SCALANCE products per Siemens ProductCERT advisory SSA-613116
  • Review and update network segmentation for industrial control systems to limit exposure of kdb-enabled systems
  • Follow CISA ICS recommended practices for defense-in-depth strategies
  • Monitor for anomalous local access attempts on systems where kernel debugging may be enabled
  • Validate that kernel debugging interfaces are disabled in production environments where not required

Evidence notes

The vulnerability description is drawn from the official CVE record and CISA CSAF advisory ICSA-25-226-15. The fix involves replacing strncpy() with safer memory operations and adding boundary checks. Siemens ProductCERT advisory SSA-613116 provides vendor-specific impact and remediation guidance.

Official resources

2025-08-12