PatchSiren cyber security CVE debrief

CVE-2024-43828 Siemens CVE debrief

A vulnerability in the Linux kernel's ext4 filesystem could cause an infinite loop during fast_commit replay. The issue stems from an uninitialized extent_status structure in ext4_es_find_extent_range(), which may contain garbage values leading to integer overflow and unbounded looping. This affects Siemens SIMATIC S7-1500 TM MFP industrial control systems that utilize the GNU/Linux subsystem. The vulnerability is locally exploitable with low attack complexity and requires low privileges, but can result in high availability impact through denial of service. 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

Industrial control system operators using Siemens SIMATIC S7-1500 TM MFP devices with the GNU/Linux subsystem enabled; security teams responsible for OT/ICS environments; Linux kernel maintainers for embedded industrial systems

Technical summary

The vulnerability exists in the ext4 filesystem's fast_commit replay mechanism. When ext4_ext_determine_insert_hole() fails to detect replay conditions and calls ext4_es_find_extent_range(), the function may return without initializing the 'es' (extent_status) variable. The uninitialized structure contains garbage values that can cause integer overflow, resulting in an infinite loop. This is classified as CWE-835 (Loop with Unreachable Exit Condition). The CVSS 3.1 vector is AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating local attack vector, low complexity, low privileges required, no user interaction, 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 anomalous CPU utilization that may indicate infinite loop conditions
Apply vendor patches when they become available
Implement defense-in-depth strategies for industrial control systems per CISA guidance

Evidence notes

The vulnerability was resolved in the upstream Linux kernel according to the CVE description, which credits Zhang Yi for identifying the root cause. The fix involves unconditionally initializing the extent_status structure in ext4_es_find_extent_range(). The issue was reproducible using fstest generic/039. Siemens has acknowledged this vulnerability affects the GNU/Linux subsystem of SIMATIC S7-1500 TM MFP devices through CISA advisory ICSA-24-102-01, with multiple revisions adding additional CVEs through September 2025.

Official resources

2024-04-09