Medium [CVE-2026-64253] clear PF_BLOCK_TS in copy_process
This medium-severity Red Hat Linux advisory covers CVE-2026-64253 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
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Summary
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.
The `copy_process()` function, responsible for creating new processes, incorrectly inherits a flag (`PF_BLOCK_TS`) from the parent process while simultaneously setting a related pointer (`current->plug`) to null in the child process. This inconsistency can lead to the kernel attempting to access a null pointer without proper validation.
A local attacker could potentially exploit this to trigger a system crash, leading to a Denial of Service (DoS). Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-476. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 9.
Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 12 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 12 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 12 days ago·verify at source
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