CVE-2026-64251 pwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next()

What is CVE-2026-64251?

CVE-2026-64251 is a high-severity use after free 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:

pwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next()

pwrseq_debugfs_seq_next() declares 'next' with __free(put_device), which causes put_device() to be called on the returned pointer when the variable goes out of scope. This results in a use-after-free since the seq_file framework receives a pointer whose reference has already been dropped.

Simply removing __free(put_device) would fix the UAF but would leak the reference acquired by bus_find_next_device(), as stop() only calls up_read(&pwrseq_sem) and never releases the device reference.

Fix this by making the reference counting consistent across all seq_file callbacks, matching the standard pattern used by PCI and SCSI:

- start(): use get_device() so it returns a referenced pointer. - next(): explicitly put_device(curr) to release the previous device's reference (no NULL check needed - the seq_file framework only calls next() while the previous return was non-NULL). - stop(): put_device(data) to release the last iterated device's reference, with a NULL guard since stop() may be called with NULL when start() returned NULL or next() reached end-of-sequence.

Weakness: CWE-416

Which versions are affected by CVE-2026-64251?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64251?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2026-64251 being exploited?

There is no known exploitation of CVE-2026-64251 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-2026-64251, DEBIAN-CVE-2026-64251, GHSA-4mm9-h7gj-362g, ROOT-OS-UBUNTU-2204-CVE-2026-64251, UBUNTU-CVE-2026-64251.