CVE-2026-64253 kernel/fork: clear PF_BLOCK_TS in copy_process()

What is CVE-2026-64253?

CVE-2026-64253 is a medium-severity vulnerability in Linux kernel, published on 24 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-476

Which versions are affected by CVE-2026-64253?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64253?

Apply the vendor's patch.

Is CVE-2026-64253 being exploited?

There is no known exploitation of CVE-2026-64253 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-64253, DEBIAN-CVE-2026-64253, GHSA-3p6p-hf89-xh98, ROOT-OS-UBUNTU-2204-CVE-2026-64253, UBUNTU-CVE-2026-64253.