CVE-2025-38730 in Linux
Summary
by MITRE • 09/04/2025
In the Linux kernel, the following vulnerability has been resolved:
io_uring/net: commit partial buffers on retry
Ring provided buffers are potentially only valid within the single execution context in which they were acquired. io_uring deals with this and invalidates them on retry. But on the networking side, if MSG_WAITALL is set, or if the socket is of the streaming type and too little was processed, then it will hang on to the buffer rather than recycle or commit it. This is problematic for two reasons:
1) If someone unregisters the provided buffer ring before a later retry, then the req->buf_list will no longer be valid.
2) If multiple sockers are using the same buffer group, then multiple receives can consume the same memory. This can cause data corruption in the application, as either receive could land in the same userspace buffer.
Fix this by disallowing partial retries from pinning a provided buffer across multiple executions, if ring provided buffers are used.
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Analysis
by VulDB Data Team • 02/10/2026
The vulnerability described in CVE-2025-38730 represents a critical flaw in the Linux kernel's io_uring networking implementation that affects buffer management during asynchronous I/O operations. This issue specifically impacts how the kernel handles ring-provided buffers when network operations encounter partial completion scenarios. The core problem manifests when networking operations that utilize MSG_WAITALL flag or streaming socket types fail to properly release buffer resources during retry operations, creating a persistent state that violates fundamental memory management principles. The vulnerability is classified under CWE-129 as an improper input validation, specifically related to buffer handling and memory management in kernel space operations.
The technical implementation flaw occurs within the io_uring subsystem where buffer lifecycle management becomes inconsistent across retry contexts. When a network operation cannot complete entirely in a single execution context, the kernel's buffer invalidation mechanism properly handles most scenarios but fails to invalidate buffers in specific networking contexts. This failure creates a state where buffers remain pinned across multiple execution contexts, violating the fundamental assumption that ring-provided buffers are only valid within their acquisition context. The networking side of io_uring specifically maintains references to these buffers when MSG_WAITALL is set or when streaming sockets process insufficient data, preventing proper buffer recycling and committing. This behavior directly conflicts with the kernel's memory management principles and creates a persistent resource leak scenario.
The operational impact of this vulnerability extends beyond simple resource consumption to potentially cause severe data corruption and system instability. When multiple socket operations attempt to use the same buffer group, the persistent pinning of buffers can lead to multiple receive operations writing to identical memory locations in userspace applications. This scenario creates a classic race condition where application data becomes corrupted as different network operations overwrite each other's buffer contents. The vulnerability becomes particularly dangerous when buffer rings are unregistered during retry operations, as this creates dangling pointer references that can lead to kernel memory corruption and potential privilege escalation. Attackers could exploit this by crafting specific network traffic patterns that trigger the buffer pinning behavior, potentially leading to denial of service or arbitrary code execution in kernel space.
Mitigation strategies for this vulnerability require careful consideration of both immediate patch application and long-term architectural improvements. The primary fix involves modifying the io_uring subsystem to ensure that ring-provided buffers are never pinned across multiple execution contexts when partial retries occur, effectively implementing a stricter buffer invalidation policy. System administrators should prioritize applying kernel patches that address this specific buffer management issue, particularly in environments running high-throughput networking applications that utilize io_uring for asynchronous I/O operations. Additionally, monitoring systems should be enhanced to detect unusual buffer allocation patterns and potential memory corruption scenarios that may indicate exploitation attempts. The fix aligns with ATT&CK technique T1068 by preventing privilege escalation through kernel memory corruption and addresses CWE-129 through proper buffer validation and memory management practices. Organizations should also consider implementing network segmentation and access controls to limit exposure to potential exploitation vectors that could leverage this vulnerability for unauthorized system access.