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). This vulnerability is rated as Moderate impact because successful exploitation requires local execution privileges and is restricted to causing a denial of service via a kernel panic, without compromising system integrity or confidentiality.
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 1 day 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 1 day ago·verify at source
Mitigation
The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 1 day ago·verify at source
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