CVE-2026-23263 in Linux
Summary
by MITRE • 03/18/2026
In the Linux kernel, the following vulnerability has been resolved:
io_uring/zcrx: fix page array leak
d9f595b9a65e ("io_uring/zcrx: fix leaking pages on sg init fail") fixed a page leakage but didn't free the page array, release it as well.
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Analysis
by VulDB Data Team • 03/24/2026
The vulnerability identified as CVE-2026-23263 represents a memory management issue within the Linux kernel's io_uring subsystem, specifically affecting the zcrx implementation. This flaw manifests as a page array leak that occurs during scatter-gather initialization failures, demonstrating a critical oversight in resource cleanup procedures. The io_uring framework serves as a high-performance asynchronous I/O interface that enables applications to efficiently handle large volumes of I/O operations, making it a crucial component for modern Linux systems. The zcrx implementation within this framework handles specific I/O patterns that involve complex memory management operations, particularly when dealing with page arrays that are allocated for scatter-gather operations.
The technical flaw stems from an incomplete memory cleanup routine where the fix for page leakage addressed the immediate issue of individual page leaks but failed to properly release the associated page array structure. This oversight creates a memory leak condition where the page array itself remains allocated in kernel memory even after the individual pages have been freed. The root cause lies in the improper handling of memory allocation and deallocation sequences during error conditions, particularly when scatter-gather initialization fails. When the io_uring subsystem encounters an error during the setup of scatter-gather lists, it should ensure complete cleanup of all allocated resources, including both individual pages and the page array structure that manages them.
The operational impact of this vulnerability extends beyond simple memory consumption, potentially leading to system instability and performance degradation over time. As the page array leak accumulates, it can contribute to memory fragmentation and gradual memory exhaustion, particularly in systems handling high volumes of I/O operations through the io_uring interface. This issue affects systems that rely heavily on asynchronous I/O operations, including database servers, web servers, and high-performance computing environments where io_uring is extensively utilized. The vulnerability is particularly concerning because it operates at the kernel level where resource leaks can have cascading effects on system stability and can potentially be exploited by malicious actors to exhaust system resources through sustained I/O operations.
This vulnerability aligns with CWE-401, which specifically addresses improper release of memory, and demonstrates characteristics consistent with the ATT&CK technique T1070.004 for Indicator Removal on Host. The incomplete cleanup mechanism represents a classic memory management error where proper resource deallocation is not implemented for all allocated structures. The fix implemented in commit d9f595b9a65e addresses the immediate issue but requires additional attention to ensure complete resource management during error conditions. Organizations should prioritize patching this vulnerability, particularly in environments where io_uring is actively used for high-throughput I/O operations, as the memory leak can compound over time and potentially lead to system crashes or degraded performance. System administrators should monitor memory usage patterns and consider implementing automated monitoring for memory consumption in applications that utilize the io_uring subsystem, as this vulnerability can manifest as gradual memory bloat rather than immediate system failure.