CVE-2025-37751 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
x86/cpu: Avoid running off the end of an AMD erratum table
The NULL array terminator at the end of erratum_1386_microcode was removed during the switch from x86_cpu_desc to x86_cpu_id. This causes readers to run off the end of the array.
Replace the NULL.
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Analysis
by VulDB Data Team • 03/15/2026
The vulnerability CVE-2025-37751 represents a critical memory access issue within the Linux kernel's x86 CPU subsystem that arises from improper handling of AMD processor erratum tables. This flaw specifically affects the microcode update mechanism that manages known processor defects and workarounds. The vulnerability stems from a regression introduced during kernel development when the transition occurred from the x86_cpu_desc structure to the x86_cpu_id structure. During this refactoring process, the NULL array terminator that normally bounds the erratum_1386_microcode array was inadvertently removed, creating a condition where code readers may attempt to access memory beyond the allocated array boundaries. This type of vulnerability falls under the category of buffer over-read conditions as classified by CWE-125, where software reads data past the end of a buffer or array, potentially leading to unpredictable behavior or system instability.
The technical implementation of this vulnerability involves the microcode handling subsystem that processes AMD processor errata information to ensure proper system operation and prevent hardware-level issues. When the kernel attempts to iterate through the erratum_1386_microcode table, it expects a clear termination marker to prevent traversal beyond valid data boundaries. Without the NULL terminator, the iteration logic continues reading memory locations that may contain arbitrary data or even invalid memory regions, creating potential security implications and system reliability concerns. This flaw demonstrates a classic memory safety issue that can be exploited to cause denial of service conditions or potentially enable more sophisticated attack vectors depending on the execution context. The vulnerability directly impacts the kernel's CPU detection and microcode application mechanisms, which are fundamental to system stability and security.
The operational impact of CVE-2025-37751 extends beyond simple memory access violations to encompass potential system stability and security implications for Linux systems running on AMD processors. Systems utilizing affected kernel versions may experience unexpected crashes, system hangs, or unpredictable behavior when the microcode update subsystem attempts to process the erratum table. This vulnerability is particularly concerning in server environments where system reliability is paramount, as it could lead to service disruptions or require unexpected system reboots. The flaw represents a regression that could affect systems running various kernel versions, potentially impacting enterprise deployments, cloud infrastructure, and embedded systems that rely on proper microcode handling for processor stability. Organizations deploying affected kernels may need to implement immediate patching strategies to prevent system instability or potential exploitation scenarios.
Mitigation strategies for CVE-2025-37751 primarily involve applying the appropriate kernel security patches that restore the missing NULL array terminator in the erratum_1386_microcode table. System administrators should prioritize updating to kernel versions that include the fix, which typically involves applying patches that maintain proper array bounds checking in the microcode handling subsystem. The fix addresses the root cause by reintroducing the expected NULL termination marker that prevents the array traversal logic from accessing invalid memory locations. Organizations should also consider monitoring their systems for any unusual behavior or crashes that might indicate exploitation attempts, though this specific vulnerability is more likely to manifest as system instability rather than direct exploitation. This remediation aligns with standard security practices for buffer overflow vulnerabilities and follows the ATT&CK framework's approach to addressing system-level memory safety issues through proper code review and patch management procedures. The fix demonstrates the importance of maintaining proper array bounds checking and the potential impact of seemingly minor code refactoring operations on system stability and security.