CVE-2025-39900

MEDIUM EPSS 3.2%
Published Oct 1, 20259mo ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Oct 1, 2025 9mo ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: net_sched: gen_estimator: fix est_timer() vs CONFIG_PREEMPT_RT=y syzbot reported a WARNING in est_timer() [1] Problem here is that with CONFIG_PREEMPT_RT=y, timer callbacks can be preempted. Adopt preempt_disable_nested()/preempt_enable_nested() to fix this. [1] WARNING: CPU: 0 PID: 16 at ./include/linux/seqlock.h:221 __seqprop_assert include/linux/seqlock.h:221 [inline] WARNING: CPU: 0 PID: 16 at ./include/linux/seqlock.h:221 est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:__seqprop_assert include/linux/seqlock.h:221 [inline] RIP: 0010:est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93 Call Trace: <TASK> call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747 expire_timers kernel/time/timer.c:1798 [inline] __run_timers kernel/time/timer.c:2372 [inline] __run_timer_base+0x648/0x970 kernel/time/timer.c:2384 run_timer_base kernel/time/timer.c:2393 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403 handle_softirqs+0x22c/0x710 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] run_ktimerd+0xcf/0x190 kernel/softirq.c:1043 smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
3.2% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Affected Products 6

VendorProductVersionRange
linuxlinux_kernel*≥6.12  –  <6.12.46
linuxlinux_kernel*≥6.13  –  <6.16.6
linuxlinux_kernel6.17any
linuxlinux_kernel6.17any
linuxlinux_kernel6.17any
linuxlinux_kernel6.17any

References 3

  • git.kernel.org https://git.kernel.org/stable/c/9f74c0ea9b26d1505d55b61e36b1623dd347e1d1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a22ec2ee824be30803068a52f78f7ffe3bc879fb
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e79923824c48b930609680be04cb29253fc4a17d
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/9f74c0ea9b26d1505d55b61e36b1623dd347e1d1
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a22ec2ee824be30803068a52f78f7ffe3bc879fb
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e79923824c48b930609680be04cb29253fc4a17d
    Patch