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

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-24 · updated 2026-08-17
Weakness: CWE-416

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.

Affected products

Linux kernel: from 6.11 before 6.12.95; from 6.13 before 6.18.38; from 6.19 before 7.1.3 — fixed in 6.12.95, 6.18.38, 7.1.3

How to fix

Upgrade to a fixed version: Linux kernel 6.12.95, 6.18.38, 7.1.3. Check the vendor advisory for mitigations.

References

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