CVE-2026-74709
Received Received - Intake

XSK Metadata Pointer Clear for Timestamp Handling

Vulnerability report for CVE-2026-74709, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-22

Last updated on: 2026-08-22

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: xsk: clear metadata pointer when no timestamp is requested User space can change metadata flags after request processing. Rereading them during completion can therefore make the kernel write a timestamp that was not requested when the packet was submitted. Clear the metadata pointer during request processing unless timestamp completion is requested. Completion handling can then use the pointer itself instead of rereading the flags. On the mlx5 multi-packet WQE path metadata is evaluated per batch: xsk_tx_metadata_request() runs only for the descriptor that starts a session, just like the checksum offload that is applied once through the shared WQE. Only that descriptor's pointer is reset, so completion handling can record a timestamp for the other descriptors of the session regardless of their own XDP_TXMD_FLAGS_TIMESTAMP bit. The write stays inside the metadata area; the single-WQE, other zero-copy, and generic paths reset the pointer per descriptor and are unaffected.

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves metadata handling in AF_XDP sockets. When a user space application submits packets without requesting timestamps, the kernel may incorrectly write a timestamp during completion if metadata flags were altered after submission. The fix clears the metadata pointer during request processing unless timestamp completion is explicitly requested.

Detection Guidance

This vulnerability is specific to the Linux kernel's XSK (AF_XDP) subsystem and may not have direct detection commands. Monitoring for unexpected timestamps in packet metadata or kernel logs related to XDP_TXMD_FLAGS_TIMESTAMP could indicate exploitation. Check kernel logs with 'dmesg | grep XSK' or 'journalctl -k | grep XSK'.

Impact Analysis

If exploited, this flaw could lead to unintended timestamp insertion in packet metadata, potentially causing timing inconsistencies or misattribution of packets. This may affect applications relying on accurate packet timestamps for logging, debugging, or performance monitoring.

Mitigation Strategies

Update the Linux kernel to the latest stable version where this vulnerability is patched. If immediate patching is not possible, disable AF_XDP sockets or restrict their usage until the kernel is updated. Monitor kernel security advisories for further updates.

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