CVE-2025-39736: Debian Linux

Medium severity, CVSS 5.5. EPSS: 0.1% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock When netpoll is enabled, calling pr_warn_once() while holding kmemleak_lock in mem_pool_alloc() can cause a deadlock due to lock inversion with the netconsole subsystem. This occurs because pr_warn_once() may trigger netpoll, which eventually leads to __alloc_skb() and back into kmemleak code, attempting to reacquire kmemleak_lock. This is the path for the deadlock. mem_pool_alloc() -> raw_spin_lock_irqsave(&kmemleak_lock, flags); -> pr_warn_once() -> netconsole subsystem -> netpoll -> __alloc_skb -> __create_object -> raw_spin_lock_irqsave(&kmemleak_lock, flags); Fix this by setting a flag and issuing the pr_warn_once() after kmemleak_lock is released.

Affected products

• Debian Debian Linux: version 11.0 only
• Linux Linux Kernel: from 5.4, before 5.4.297 (fixed in 5.4.297); from 5.5, before 5.10.241 (fixed in 5.10.241); from 5.11, before 5.15.190 (fixed in 5.15.190); from 5.16, before 6.1.149 (fixed in 6.1.149); from 6.2, before 6.6.103 (fixed in 6.6.103); from 6.7, before 6.12.43 (fixed in 6.12.43); …

Published 2025-09-11. Last modified 2026-06-17.