CVE-2026-74710 in Linux
Summary
by MITRE • 08/22/2026
In the Linux kernel, the following vulnerability has been resolved:
xsk: require at least 16 bytes of TX metadata
AF_XDP accepts a TX metadata length as small as eight bytes, but every supported request needs the flags plus at least one eight-byte request field. Such short metadata also lets the kernel read beyond the registered area.
Require 16 bytes rather than sizeof(struct xsk_tx_metadata) to preserve compatibility with applications that do not use launch-time metadata.
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Analysis
by VulDB Data Team • 08/22/2026
The Linux kernel vulnerability identified in the AF_XDP subsystem involves an insufficient validation of transmit metadata length, which allows for out-of-bounds memory reads and potential information disclosure or system instability. The Address Family eXpress Data Path (AF_XDP) interface is designed to facilitate high-performance packet processing by allowing user-space applications to bypass traditional kernel networking stacks. Within this framework, the transmission path accepts a parameter specifying the length of metadata associated with each transmitted packet. Prior to the fix, the implementation permitted this metadata length to be as small as eight bytes. This lower bound was technically insufficient because every supported request type requires not only flags but also at least one additional eight-byte field for proper operation. Consequently, when an application provided a metadata buffer that was too short, the kernel would attempt to read beyond the boundaries of the registered user-space memory area during packet processing.
This out-of-bounds access represents a critical security flaw classified under CWE-125, which denotes Out-of-Bounds Read vulnerabilities. By reading data from memory locations outside the intended buffer, an attacker or malicious application could potentially leak sensitive kernel information that resides in adjacent memory regions. In worst-case scenarios, if the read operation triggers specific fault handling paths or interacts with other subsystems unpredictably, it could lead to a denial of service condition by crashing the network stack or destabilizing the host system. The vulnerability stems from a lack of strict boundary checks on user-supplied metadata lengths before they are utilized in kernel operations that assume a minimum structural size for data integrity and safety.
The operational impact of this flaw is significant for environments relying on AF_XDP for high-throughput networking, such as cloud infrastructure or network function virtualization platforms. Attackers with access to the system could exploit this weakness by crafting specific XDP programs or socket configurations that trigger the out-of-bounds read during packet transmission. This exploitation vector does not necessarily require privilege escalation if the primary goal is information disclosure of kernel memory contents, which can aid in further attacks such as bypassing Address Space Layout Randomization (ASLR). Furthermore, repeated triggering of this condition could degrade system performance or cause intermittent crashes, affecting service availability for other processes sharing the same kernel instance.
To mitigate this vulnerability, the Linux kernel developers have implemented a mandatory requirement that transmit metadata must be at least sixteen bytes in length. This change ensures that there is always sufficient space to accommodate both the flags and the required request fields without encroaching on unallocated or protected memory regions. The selection of sixteen bytes rather than strictly sizeof(struct xsk_tx_metadata) was a deliberate design choice aimed at preserving backward compatibility with existing applications that do not utilize launch-time metadata features but still rely on valid buffer allocations for other purposes. System administrators should ensure their kernels are updated to include this patch, and developers using AF_XDP must verify that their application logic allocates buffers meeting the new minimum size requirement before submitting packets to the kernel. This alignment with industry standards such as CWE-125 reinforces the importance of rigorous input validation in systems programming to prevent memory safety violations.