Linux Kernel pwrseq DebugFS UAF Vulnerability
CVE-2026-64251 Published on July 24, 2026
pwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next()
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.
Products Associated with CVE-2026-64251
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Affected Versions
Linux:- Version 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c and below ba0b9f04c7a5f9887b8ce672eaf049502c0548ec is affected.
- Version 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c and below e91df6d273445c03f5aa302bfe147eda33d45794 is affected.
- Version 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c and below 73569a44fca2992f0ca4a4c0104069741b9873a0 is affected.
- Version 249ebf3f65f8530beb2cbfb91bff1d83ba88d23c and below 257595adf9dac15ae1edd9d07753fbc576a7583d is affected.
- Version 6.11 is affected.
- Before 6.11 is unaffected.
- Version 6.12.95, <= 6.12.* is unaffected.
- Version 6.18.38, <= 6.18.* is unaffected.
- Version 7.1.3, <= 7.1.* is unaffected.
- Version 7.2-rc1, <= * is unaffected.