CVE-2026-64253
Received Received - Intake

Race Condition in Linux Kernel PF_BLOCK_TS Handling

Publication date: 2026-07-24

Last updated on: 2026-07-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: kernel/fork: clear PF_BLOCK_TS in copy_process() PF_BLOCK_TS is only set in blk_time_get_ns() when current->plug is non-NULL, and blk_finish_plug() clears it via __blk_flush_plug() before NULLing the plug pointer. copy_process() breaks the invariant by inheriting PF_BLOCK_TS from the parent while resetting the child's plug to NULL. Clear PF_BLOCK_TS alongside that assignment so callers can rely on "PF_BLOCK_TS set implies current->plug != NULL" and dereference current->plug unguarded.

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Meta Information

Published
2026-07-24
Last Modified
2026-07-24
Generated
2026-07-24
AI Q&A
2026-07-24
EPSS Evaluated
N/A
NVD
CVE-2026-64253
EUVD
EUVD-2026-48662

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 a flaw in the process creation logic where the PF_BLOCK_TS flag is incorrectly inherited from the parent process to the child process during fork operations. This breaks an invariant that assumes PF_BLOCK_TS is only set when a process has an active plug, leading to potential dereferencing of a null pointer.

Detection Guidance

This vulnerability is specific to the Linux kernel and requires kernel-level detection. Check your kernel version with 'uname -r' and compare it against patched versions. Monitor kernel logs for unusual process behavior or crashes related to process forking or block I/O operations.

Impact Analysis

This vulnerability could cause kernel crashes or instability if exploited, as it may lead to null pointer dereferences in the block layer. Users running affected Linux kernel versions might experience system freezes, data corruption, or denial of service conditions.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it is a low-level kernel issue related to process management and block I/O operations. There is no evidence it impacts data protection, privacy, or security controls required by these regulations.

Mitigation Strategies

Update your Linux kernel to the latest patched version immediately. If immediate patching is not possible, restrict access to untrusted users and avoid running untrusted applications. Monitor system logs for signs of exploitation.

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