CVE-2026-31689
Published: 27 April 2026
Summary
CVE-2026-31689 is a medium-severity NULL Pointer Dereference (CWE-476) vulnerability in Linux Linux Kernel. Its CVSS base score is 5.5 (Medium).
Operationally, ranked at the 1.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
This vulnerability is AI-related — categorised as Other Platforms; in the Not Applicable risk domain.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and SA-11 (Developer Testing and Evaluation).
Deeper analysis
CVE-2026-31689 affects the Linux kernel's EDAC/mc subsystem in the edac_mc_alloc() function. The vulnerability arises from incorrect error path ordering: when the mci->pvt_info allocation fails, put_device() is called before device_initialize(), leading to kobject_put() on an uninitialized kobject and resulting in kernel warnings. This issue was observed in kernel version 7.0.0-rc1 during amd64_edac module initialization.
The vulnerability triggers in error paths during EDAC operations, as seen in a kernel trace involving systemd-udevd on CPU 22. Local system processes like udevd can encounter it under allocation failure conditions, producing warnings such as "kobject: '(null)': is not initialized, yet kobject_put() is being called" and stack traces from edac_mc_alloc() and amd64_edac_init(). No specific exploitation for code execution or escalation is detailed.
Kernel stable patches address the issue by reordering the initialization sequence to ensure device_initialize() precedes potential error paths that call put_device(). Relevant commits include https://git.kernel.org/stable/c/51520e03e70d6c73e33ee7cbe0319767d05764fe, https://git.kernel.org/stable/c/75825648ce984ca4cebb28e4bd2bf8c3a7e837c5, https://git.kernel.org/stable/c/87ce8ae511962e105bcb3534944208c6a9471ed9, https://git.kernel.org/stable/c/aae95970fad2127a1bd49d8713c7cd0677dcd2d6, and https://git.kernel.org/stable/c/d20e98c2df9354cc744431ad8ccbf49405b8b40f.
This vulnerability was identified by Claude while reviewing another EDAC patch, with no reported real-world exploitation.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-25886
Vulnerability details
In the Linux kernel, the following vulnerability has been resolved: EDAC/mc: Fix error path ordering in edac_mc_alloc() When the mci->pvt_info allocation in edac_mc_alloc() fails, the error path will call put_device() which will end up calling the device's release function. However,…
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the init ordering is wrong such that device_initialize() happens *after* the failed allocation and thus the device itself and the release function pointer are not initialized yet when they're called: MCE: In-kernel MCE decoding enabled. ------------[ cut here ]------------ kobject: '(null)': is not initialized, yet kobject_put() is being called. WARNING: lib/kobject.c:734 at kobject_put, CPU#22: systemd-udevd CPU: 22 UID: 0 PID: 538 Comm: systemd-udevd Not tainted 7.0.0-rc1+ #2 PREEMPT(full) RIP: 0010:kobject_put Call Trace: <TASK> edac_mc_alloc+0xbe/0xe0 [edac_core] amd64_edac_init+0x7a4/0xff0 [amd64_edac] ? __pfx_amd64_edac_init+0x10/0x10 [amd64_edac] do_one_initcall ... Reorder the calling sequence so that the device is initialized and thus the release function pointer is properly set before it can be used. This was found by Claude while reviewing another EDAC patch.
- CWE(s)
AI Security AnalysisAI
- AI Category
- Other Platforms
- Risk Domain
- Not Applicable
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: claude
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Insufficient information to map techniques.CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly addresses the CVE by requiring timely application of the kernel patches that reorder device_initialize() before any error-path put_device() call in edac_mc_alloc().
Requires developer testing and evaluation (including error-path and negative-condition testing) that would have exposed the uninitialized kobject usage during allocation failure.
Mandates use of secure development processes and tools that enforce correct initialization ordering and release-function setup before any put_device() invocation.