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PatchSiren cyber security CVE debrief

CVE-2024-49900 Siemens CVE debrief

This CVE addresses an uninitialized memory vulnerability in the Linux kernel's Journaled File System (JFS) implementation. The issue stems from improper initialization of the `new_ea` field within the `ea_buffer` structure used during extended attribute operations. When `ea_get()` allocates the `ea_buf` structure, the `new_ea` member was not zeroed, leading to use of uninitialized values that could propagate through `ea_put()` and eventually reach compression routines like `lzo1x_1_do_compress()`. The vulnerability was detected by syzbot using Kernel Memory Sanitizer (KMSAN), which flagged the uninitialized value usage in the compression path. The fix involves adding a `memset()` call at the beginning of `ea_get()` to ensure the `ea_buf` structure, including `new_ea`, is properly zeroed before use. This is a classic uninitialized memory bug that could potentially lead to information disclosure or undefined behavior depending on how the uninitialized data is subsequently used. The vulnerability affects the JFS extended attribute code paths (`__jfs_setxattr`, `__jfs_xattr_set`) and was resolved by ensuring proper initialization of the buffer structure.

Vendor
Siemens
Product
RUGGEDCOM RST2428P (6GK6242-6PA00)
CVSS
HIGH 7.1
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 running Linux systems with JFS filesystem support enabled, particularly industrial control systems and OT environments using affected Siemens products that incorporate vulnerable kernel versions. System administrators responsible for kernel security patching and filesystem configuration should prioritize this fix.

Technical summary

The Linux kernel's JFS filesystem implementation contained an uninitialized memory vulnerability in the extended attribute handling code. The `ea_buffer` structure's `new_ea` field was not initialized when allocated in `ea_get()`, leading to use of uninitialized values that could propagate through `ea_put()` and reach compression functions. The vulnerability was detected by syzbot using KMSAN. The fix adds `memset()` initialization of the `ea_buf` structure in `ea_get()` to ensure proper zeroing before use.

Defensive priority

medium

Recommended defensive actions

  • Review kernel configurations to determine if JFS filesystem support is enabled and required for operational use
  • Apply vendor-provided kernel updates that include the fix for uninitialized `ea_buf->new_ea` in JFS extended attribute handling
  • If JFS is not required, consider disabling JFS support via kernel module blacklist or configuration changes to reduce attack surface
  • Monitor for kernel memory sanitizer (KMSAN) warnings in development and testing environments that may indicate similar uninitialized memory issues
  • Validate that extended attribute operations on JFS filesystems function correctly after applying patches

Evidence notes

The vulnerability was identified through automated kernel fuzzing (syzbot with KMSAN). The fix commit initializes the `ea_buf` structure via `memset()` in `ea_get()` to prevent propagation of uninitialized `new_ea` data through `ea_put()` to downstream consumers including LZO compression routines.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-49900 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-49900

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2024-49900 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-49900

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2025/icsa-25-226-07.json

    cisa_csaf

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/csaf/ssa-355557.json

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://cert-portal.siemens.com/productcert/html/ssa-355557.html

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-advisories/icsa-25-226-07

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/news-events/ics-alerts/ics-alert-10-301-01

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/resources-tools/resources/ics-recommended-practices

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/topics/industrial-control-systems

    Reference

  • Source reference

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf

    Reference

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.