DEBIAN-CVE-2025-39977

Advisory lineage Upstream: 1 Downstream: 2
Upstream
CVE-2025-39977
Published: 15 Oct 2025, 08:15
Last modified:28 Apr 2026, 20:30

Vulnerability Summary

Overall Risk (default)
minimal
0/100
CVSS Score
No data
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

15 Oct 2025, 08:15
Published
Vulnerability first disclosed
28 Apr 2026, 20:30
Last Modified
Vulnerability information updated

Description

In the Linux kernel, the following vulnerability has been resolved: futex: Prevent use-after-free during requeue-PI syzbot managed to trigger the following race: T1 T2 futex_wait_requeue_pi() futex_do_wait() schedule() futex_requeue() futex_proxy_trylock_atomic() futex_requeue_pi_prepare() requeue_pi_wake_futex() futex_requeue_pi_complete() /* preempt */ * timeout/ signal wakes T1 * futex_requeue_pi_wakeup_sync() // Q_REQUEUE_PI_LOCKED futex_hash_put() // back to userland, on stack futex_q is garbage /* back */ wake_up_state(q->task, TASK_NORMAL); In this scenario futex_wait_requeue_pi() is able to leave without using futex_q::lock_ptr for synchronization. This can be prevented by reading futex_q::task before updating the futex_q::requeue_state. A reference on the task_struct is not needed because requeue_pi_wake_futex() is invoked with a spinlock_t held which implies a RCU read section. Even if T1 terminates immediately after, the task_struct will remain valid during T2's wake_up_state(). A READ_ONCE on futex_q::task before futex_requeue_pi_complete() is enough because it ensures that the variable is read before the state is updated. Read futex_q::task before updating the requeue state, use it for the following wakeup.

Affected Systems

  • debian•linux

    < 6.1.158-1 | < 6.12.57-1 | < 6.16.10-1

  • debian•linux-6.1

    < 6.1.158-1~deb11u1

References (1)