CVE-2026-64256
Received Received - Intake

XFS Quota ID Wrap-Around Vulnerability in Linux Kernel

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: xfs: don't wrap around quota ids in dqiterate LOLLM noticed that q_id is an unsigned 32-bit variable. If it happens to be set to XFS_DQ_ID_MAX due to a filesystem that actually has a dquot for ID_MAX, then this addition will truncate to zero and the iteration starts over. Fix this by casting to u64.

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64256
EUVD
EUVD-2026-48968

Affected Vendors & Products

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

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a flaw in the XFS filesystem's quota handling. The issue occurs when processing quota IDs during iteration. The q_id variable is an unsigned 32-bit integer, and if set to XFS_DQ_ID_MAX, an addition operation causes it to wrap around to zero, restarting the iteration process incorrectly.

Detection Guidance

This vulnerability is specific to the XFS filesystem in the Linux kernel and involves quota ID handling. Detection requires checking kernel logs for quota-related errors or filesystem corruption. Commands like dmesg | grep -i quota or journalctl -k | grep -i xfs may help identify issues. Ensure your kernel is updated to the patched version.

Impact Analysis

This vulnerability could lead to incorrect quota management in XFS filesystems. It may cause the system to miscalculate disk usage or enforce quotas improperly, potentially resulting in unauthorized disk space usage or denial of service due to incorrect quota enforcement.

Mitigation Strategies

Apply the latest kernel update from your distribution to patch this issue. If immediate patching is not possible, disable XFS quota functionality temporarily as a workaround. Monitor filesystem logs for quota-related errors and back up critical data.

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