CVE-2026-23094 in Linux
Summary
by MITRE • 02/04/2026
In the Linux kernel, the following vulnerability has been resolved:
uacce: fix isolate sysfs check condition
uacce supports the device isolation feature. If the driver implements the isolate_err_threshold_read and isolate_err_threshold_write callback functions, uacce will create sysfs files now. Users can read and configure the isolation policy through sysfs. Currently, sysfs files are created as long as either isolate_err_threshold_read or isolate_err_threshold_write callback functions are present.
However, accessing a non-existent callback function may cause the system to crash. Therefore, intercept the creation of sysfs if neither read nor write exists; create sysfs if either is supported, but intercept unsupported operations at the call site.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability identified as CVE-2026-23094 resides within the Linux kernel's Unified Acceleration Core (uacce) subsystem, which provides a framework for managing hardware acceleration devices. This flaw represents a critical design oversight in the device isolation mechanism that could potentially lead to system instability and crashes. The uacce subsystem implements device isolation features through sysfs interfaces that allow administrators to configure isolation policies based on error thresholds, making it an essential component for maintaining system security and reliability in environments utilizing hardware acceleration capabilities. The vulnerability manifests in how the subsystem handles callback function validation during sysfs file creation, creating a potential attack surface that could be exploited to cause system-wide disruptions.
The technical flaw stems from an incorrect conditional logic implementation within the uacce driver's sysfs file creation process. Currently, the subsystem creates sysfs files whenever either the isolate_err_threshold_read or isolate_err_threshold_write callback functions are implemented, regardless of whether both functions exist or if the implementation is complete. This approach creates a dangerous scenario where accessing non-existent callback functions can trigger kernel crashes due to null pointer dereferences or invalid memory accesses. The flaw directly relates to CWE-476 which describes null pointer dereference vulnerabilities, and more specifically aligns with CWE-119 which addresses memory access violations. The improper validation creates a race condition where the system attempts to expose functionality that does not exist, potentially allowing malicious actors or faulty code paths to trigger kernel panics through crafted sysfs access attempts.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the entire system stability and availability. When the uacce subsystem attempts to create sysfs interfaces for device isolation policies without proper validation of callback function existence, it creates a scenario where legitimate system operations can fail catastrophically. This vulnerability affects systems running Linux kernels that incorporate the uacce subsystem, particularly those utilizing hardware acceleration devices that rely on this isolation mechanism. The potential for system crashes during normal operation or during device configuration processes could result in denial of service conditions, data loss, or the need for system reboots. From an attacker perspective, this represents a potential privilege escalation vector or a means to cause persistent system instability that could be exploited in targeted attacks against infrastructure relying on hardware acceleration.
Mitigation strategies for this vulnerability require immediate kernel updates that implement proper callback validation before sysfs file creation. The fix should intercept sysfs creation when neither read nor write callback functions exist, ensuring that sysfs interfaces are only created when both functions are properly implemented. Additionally, the solution must implement proper error handling at the call site to intercept unsupported operations rather than allowing them to proceed to potentially crash the kernel. Organizations should prioritize updating their kernel versions to include the patched uacce subsystem, while system administrators should monitor for any unusual system behavior or crashes related to hardware acceleration devices. The fix aligns with ATT&CK technique T1068 which involves privilege escalation through kernel exploits, and T1490 which covers denial of service attacks targeting system resources. Security teams should also implement monitoring for anomalous sysfs access patterns in environments where uacce devices are present, as these could indicate exploitation attempts or misconfigurations that may trigger the vulnerable code path.