CVE-2026-23123 Overview
A vulnerability has been identified in the Linux kernel's interconnect debugfs subsystem involving uninitialized memory use. The debugfs_create_str() API assumes that the string pointer is either NULL or points to valid kmalloc() memory. When the src_node and dst_node pointers are left uninitialized before creating debugfs entries, it can lead to unsafe memory access conditions during read and write operations.
Critical Impact
Uninitialized memory pointers in the interconnect debugfs interface could cause system instability or allow unpredictable behavior when debugfs entries are accessed.
Affected Products
- Linux kernel (interconnect debugfs subsystem)
Discovery Timeline
- 2026-02-14 - CVE CVE-2026-23123 published to NVD
- 2026-02-18 - Last updated in NVD database
Technical Details for CVE-2026-23123
Vulnerability Analysis
This vulnerability falls under the category of Uninitialized Memory Use within the Linux kernel's interconnect debugfs subsystem. The issue stems from improper initialization of string pointers (src_node and dst_node) that are subsequently passed to the debugfs_create_str() API function.
The debugfs_create_str() function is designed to create debugfs entries that expose string values to userspace for debugging purposes. This API has a critical assumption: the string pointer passed to it must either be NULL or must point to memory that was allocated via kmalloc(). When uninitialized pointers are used instead, the function may attempt to dereference arbitrary memory addresses, leading to unpredictable behavior.
The vulnerability exists in the interconnect subsystem's debugfs initialization path, where node identifiers are exposed for debugging purposes without proper pre-initialization of the underlying string pointers.
Root Cause
The root cause of this vulnerability is the failure to initialize the src_node and dst_node string pointers before passing them to the debugfs_create_str() API. In C, local or dynamically allocated variables that are not explicitly initialized contain indeterminate values. When these uninitialized pointers are used with debugfs, subsequent read or write operations may access invalid memory locations.
The fix involves initializing these pointers to empty strings before the debugfs entries are created, ensuring that all subsequent memory access operations are performed on valid, allocated memory.
Attack Vector
The attack vector for this vulnerability is through the debugfs filesystem interface. An attacker with access to the debugfs mount point (typically at /sys/kernel/debug/) could potentially trigger the vulnerability by reading from or writing to the affected debugfs entries. This would cause the kernel to dereference the uninitialized pointers, potentially leading to:
- Kernel crashes or system instability
- Information disclosure if the uninitialized pointer happens to reference readable kernel memory
- Denial of service through repeated exploitation
Note that debugfs access typically requires root privileges or specific capabilities, which limits the attack surface in production environments.
Detection Methods for CVE-2026-23123
Indicators of Compromise
- Kernel crashes or oops messages referencing the interconnect debugfs subsystem
- Unexpected system instability when accessing debugfs entries under the interconnect path
- Kernel log messages indicating invalid memory access in interconnect-related functions
Detection Strategies
- Monitor kernel logs for memory access violations or oops messages related to debugfs operations
- Audit access to /sys/kernel/debug/interconnect/ paths for suspicious activity
- Implement kernel crash dump analysis to identify exploitation attempts
Monitoring Recommendations
- Enable kernel debugging features to capture detailed crash dumps for analysis
- Configure system monitoring to alert on kernel panics or oops events
- Review debugfs access logs if audit logging is enabled for the filesystem
How to Mitigate CVE-2026-23123
Immediate Actions Required
- Update the Linux kernel to a patched version that includes the fix for this vulnerability
- Restrict access to debugfs by unmounting it in production environments where debugging is not required
- Implement access controls to limit debugfs access to only authorized administrators
Patch Information
The Linux kernel maintainers have released patches to address this vulnerability. The fix initializes src_node and dst_node to empty strings before creating the debugfs entries, ensuring safe memory access during read and write operations.
Patches are available through the official kernel git repositories:
Workarounds
- Unmount debugfs in production environments where kernel debugging is not actively needed using umount /sys/kernel/debug
- Restrict debugfs mount permissions to root-only access if unmounting is not feasible
- Consider using kernel module parameters or boot options to disable the interconnect debugfs interface if available
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
