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CVE-2025-39900— net_sched: gen_estimator: fix est_timer() vs CONFIG_PREEMPT_RT=y

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于est_timer与CONFIG_PREEMPT_RT配置存在竞争条件，可能导致空指针取消引用。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.15% · P4

Possible ATT&CK Techniques 1 AI

T1200 · Hardware Additions

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux d2d6422f8bd17c6bb205133e290625a564194496< a22ec2ee824be30803068a52f78f7ffe3bc879fb affected
d2d6422f8bd17c6bb205133e290625a564194496< e79923824c48b930609680be04cb29253fc4a17d affected
d2d6422f8bd17c6bb205133e290625a564194496< 9f74c0ea9b26d1505d55b61e36b1623dd347e1d1 affected
6.12 affected
< 6.12 unaffected
6.12.46≤ 6.12.* unaffected
6.16.6≤ 6.16.* unaffected
6.17≤ * unaffected
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I. Basic Information for CVE-2025-39900

Vulnerability Information
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Vulnerability Title
net_sched: gen_estimator: fix est_timer() vs CONFIG_PREEMPT_RT=y
Source: CVE Program / CVE List V5
Vulnerability 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>
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于est_timer与CONFIG_PREEMPT_RT配置存在竞争条件，可能导致空指针取消引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux d2d6422f8bd17c6bb205133e290625a564194496 ~ a22ec2ee824be30803068a52f78f7ffe3bc879fb -
Linux Linux 6.12 -

II. Public POCs for CVE-2025-39900

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III. Intelligence Information for CVE-2025-39900

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Patches & Fixes for CVE-2025-39900 (2)

Same Patch Batch · Linux · 2025-10-01 · 169 CVEs total

CVE-2023-53517 9.8 CRITICAL tipc: do not update mtu if msg_max is too small in mtu negotiation
CVE-2025-39919 8.8 HIGH wifi: mt76: mt7996: add missing check for rx wcid entries
CVE-2025-39918 8.8 HIGH wifi: mt76: fix linked list corruption
CVE-2023-53454 8.8 HIGH HID: multitouch: Correct devm device reference for hidinput input_dev name
CVE-2022-50442 8.4 HIGH fs/ntfs3: Validate buffer length while parsing index
CVE-2023-53493 8.4 HIGH accel/qaic: tighten bounds checking in decode_message()
CVE-2023-53492 7.8 HIGH netfilter: nf_tables: do not ignore genmask when looking up chain by id
CVE-2025-39924 7.8 HIGH erofs: fix invalid algorithm for encoded extents
CVE-2023-53510 7.8 HIGH scsi: ufs: core: Fix handling of lrbp->cmd
CVE-2025-39927 7.8 HIGH ceph: fix race condition validating r_parent before applying state
CVE-2022-50421 7.8 HIGH rpmsg: char: Avoid double destroy of default endpoint
CVE-2023-53506 7.8 HIGH udf: Do not bother merging very long extents
CVE-2022-50423 7.8 HIGH ACPICA: Fix use-after-free in acpi_ut_copy_ipackage_to_ipackage()
CVE-2023-53504 7.8 HIGH RDMA/bnxt_re: Properly order ib_device_unalloc() to avoid UAF
CVE-2023-53495 7.8 HIGH net: ethernet: mvpp2_main: fix possible OOB write in mvpp2_ethtool_get_rxnfc()
CVE-2023-53494 7.8 HIGH crypto: xts - Handle EBUSY correctly
CVE-2022-50437 7.8 HIGH drm/msm/hdmi: fix memory corruption with too many bridges
CVE-2023-53478 7.8 HIGH tracing/synthetic: Fix races on freeing last_cmd
CVE-2023-53481 7.8 HIGH ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed
CVE-2023-53486 7.8 HIGH fs/ntfs3: Enhance the attribute size check

Showing top 20 of 169 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-39900

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