# CVE-2025-38727

## Summary

- **CVE ID:** CVE-2025-38727
- **Severity:** MEDIUM
- **CVSS Score:** 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** Sep 4, 2025
- **Last Modified:** Sep 8, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

netlink: avoid infinite retry looping in netlink_unicast()

netlink_attachskb() checks for the socket's read memory allocation
constraints. Firstly, it has:

  rmem < READ_ONCE(sk->sk_rcvbuf)

to check if the just increased rmem value fits into the socket's receive
buffer. If not, it proceeds and tries to wait for the memory under:

  rmem + skb->truesize > READ_ONCE(sk->sk_rcvbuf)

The checks don't cover the case when skb->truesize + sk->sk_rmem_alloc is
equal to sk->sk_rcvbuf. Thus the function neither successfully accepts
these conditions, nor manages to reschedule the task - and is called in
retry loop for indefinite time which is caught as:

  rcu: INFO: rcu_sched self-detected stall on CPU
  rcu:     0-....: (25999 ticks this GP) idle=ef2/1/0x4000000000000000 softirq=262269/262269 fqs=6212
  (t=26000 jiffies g=230833 q=259957)
  NMI backtrace for cpu 0
  CPU: 0 PID: 22 Comm: kauditd Not tainted 5.10.240 #68
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc42 04/01/2014
  Call Trace:
  <IRQ>
  dump_stack lib/dump_stack.c:120
  nmi_cpu_backtrace.cold lib/nmi_backtrace.c:105
  nmi_trigger_cpumask_backtrace lib/nmi_backtrace.c:62
  rcu_dump_cpu_stacks kernel/rcu/tree_stall.h:335
  rcu_sched_clock_irq.cold kernel/rcu/tree.c:2590
  update_process_times kernel/time/timer.c:1953
  tick_sched_handle kernel/time/tick-sched.c:227
  tick_sched_timer kernel/time/tick-sched.c:1399
  __hrtimer_run_queues kernel/time/hrtimer.c:1652
  hrtimer_interrupt kernel/time/hrtimer.c:1717
  __sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113
  asm_call_irq_on_stack arch/x86/entry/entry_64.S:808
  </IRQ>

  netlink_attachskb net/netlink/af_netlink.c:1234
  netlink_unicast net/netlink/af_netlink.c:1349
  kauditd_send_queue kernel/audit.c:776
  kauditd_thread kernel/audit.c:897
  kthread kernel/kthread.c:328
  ret_from_fork arch/x86/entry/entry_64.S:304

Restore the original behavior of the check which commit in Fixes
accidentally missed when restructuring the code.

Found by Linux Verification Center (linuxtesting.org).

## Affected Products

- Linux — Linux (9da025150b7c14a8390fc06aea314c0a4011e82c)
- Linux — Linux (c4ceaac5c5ba0b992ee1dc88e2a02421549e5c98)
- Linux — Linux (fd69af06101090eaa60b3d216ae715f9c0a58e5b)
- Linux — Linux (76602d8e13864524382b0687dc32cd8f19164d5a)
- Linux — Linux (55baecb9eb90238f60a8350660d6762046ebd3bd)
- Linux — Linux (4b8e18af7bea92f8b7fb92d40aeae729209db250)
- Linux — Linux (cd7ff61bfffd7000143c42bbffb85eeb792466d6)
- Linux — Linux (ae8f160e7eb24240a2a79fc4c815c6a0d4ee16cc)
- Linux — Linux (6.16)
- Linux — Linux (0)
- Linux — Linux (5.4.297)
- Linux — Linux (5.10.241)
- Linux — Linux (5.15.190)
- Linux — Linux (6.1.149)
- Linux — Linux (6.6.103)
- Linux — Linux (6.12.43)
- Linux — Linux (6.15.11)
- Linux — Linux (6.16.2)
- Linux — Linux (6.17)
- Linux — Linux (5.4.296)
- Linux — Linux (5.10.240)
- Linux — Linux (5.15.189)
- Linux — Linux (6.1.146)
- Linux — Linux (6.6.99)
- Linux — Linux (6.12.39)
- Linux — Linux (6.15.7)

## References

- [CNA](https://git.kernel.org/stable/c/47d49fd07f86d1f55ea1083287303d237e9e0922)
- [CNA](https://git.kernel.org/stable/c/6bee383ff83352a693d03efdf27cdd80742f71b2)
- [CNA](https://git.kernel.org/stable/c/f324959ad47e62e3cadaffa65d3cff790fb48529)
- [CNA](https://git.kernel.org/stable/c/d42b71a34f6b8a2d5c53df81169b03b8d8b5cf4e)
- [CNA](https://git.kernel.org/stable/c/346c820ef5135cf062fa3473da955ef8c5fb6929)
- [CNA](https://git.kernel.org/stable/c/44ddd7b1ae0b7edb2c832eb16798c827a05e58f0)
- [CNA](https://git.kernel.org/stable/c/78fcd69d55c5f11d7694c547eca767a1cfd38ec4)
- [CNA](https://git.kernel.org/stable/c/e8edc7de688791a337c068693f22e8d8b869df71)
- [CNA](https://git.kernel.org/stable/c/759dfc7d04bab1b0b86113f1164dc1fec192b859)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-082556.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-032379.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 6.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._