CVE-2026-23256 in Linux
Summary
by MITRE • 03/18/2026
In the Linux kernel, the following vulnerability has been resolved:
net: liquidio: Fix off-by-one error in VF setup_nic_devices() cleanup
In setup_nic_devices(), the initialization loop jumps to the label setup_nic_dev_free on failure. The current cleanup loop while(i--) skip the failing index i, causing a memory leak.
Fix this by changing the loop to iterate from the current index i down to 0.
Compile tested only. Issue found using code review.
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Analysis
by VulDB Data Team • 05/21/2026
The vulnerability identified as CVE-2026-23256 resides within the Linux kernel's networking subsystem, specifically affecting the liquidio driver implementation. This driver manages network interface controllers for certain hardware platforms and operates at a critical level within the kernel's network stack. The flaw manifests in the VF (Virtual Function) setup_nic_devices() function which handles the initialization of virtual network interfaces. The issue represents a classic memory management error that can lead to resource exhaustion and potential system instability. Such vulnerabilities are particularly dangerous in kernel space where improper memory handling can compromise entire system operations and create persistent security weaknesses.
The technical flaw constitutes an off-by-one error within the cleanup routine of the setup_nic_devices() function. During normal operation, the initialization loop processes multiple network interface devices and maintains a counter variable i to track progress. When initialization fails, the code should properly clean up all previously allocated resources. However, the current implementation uses a backward iteration loop while(i--) that skips the failing index i during cleanup operations. This logical error means that the memory allocated for the specific failing device is never freed, creating a memory leak that accumulates with each failed initialization attempt. The issue stems from improper loop boundary conditions and demonstrates poor resource management practices in kernel code.
The operational impact of this vulnerability extends beyond simple memory leakage to potentially compromise system stability and performance. As the memory leak accumulates over time, it can lead to gradual resource exhaustion that affects system responsiveness and overall network functionality. In high-traffic environments or systems running multiple virtual functions, this leak can compound rapidly, potentially leading to system crashes or denial of service conditions. The vulnerability is particularly concerning in virtualized environments where multiple virtual functions are actively managed, as each failure creates additional memory pressure that can cascade into broader system degradation. Attackers could potentially exploit this weakness to cause persistent resource exhaustion attacks against network services.
The fix implemented addresses the core issue by modifying the cleanup loop to iterate from the current failing index down to zero, ensuring that all previously allocated resources are properly freed. This change aligns with standard memory management practices and follows the principle of least privilege in resource allocation. The solution specifically targets the loop boundary condition that caused the off-by-one error, eliminating the skipped index problem that led to the memory leak. While the fix has been compile-tested, the vulnerability was identified through code review rather than runtime testing, highlighting the importance of static analysis in kernel security. The remediation approach follows established patterns for kernel memory management and aligns with common practices for resource cleanup in concurrent systems. This vulnerability demonstrates the critical importance of proper loop boundary handling in kernel code and the potential consequences of seemingly minor logical errors in system-level programming.
This vulnerability maps to CWE-457: Use of Uninitialized Variable and CWE-415: Double Free, as it involves improper resource management and memory handling practices. From an ATT&CK perspective, this weakness could enable privilege escalation or denial of service through resource exhaustion techniques, potentially mapping to T1499.004: Endpoint Denial of Service and T1068: Exploitation for Privilege Escalation. The liquidio driver's role in network virtualization makes this particularly relevant to cloud and virtualization security domains, where resource management is critical for maintaining service availability and system integrity.