CVE-2025-39900
Full vulnerability record from the local CVENow database.
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>
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-10-01 08:15:32.740000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON
{
"id": "CVE-2025-39900",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-10-01T08:15:32.740",
"lastModified": "2026-10-19T21:10:00.160",
"vulnStatus": "Modified",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: gen_estimator: fix est_timer() vs CONFIG_PREEMPT_RT=y\n\nsyzbot reported a WARNING in est_timer() [1]\n\nProblem here is that with CONFIG_PREEMPT_RT=y, timer callbacks\ncan be preempted.\n\nAdopt preempt_disable_nested()/preempt_enable_nested() to fix this.\n\n[1]\n WARNING: CPU: 0 PID: 16 at ./include/linux/seqlock.h:221 __seqprop_assert include/linux/seqlock.h:221 [inline]\n WARNING: CPU: 0 PID: 16 at ./include/linux/seqlock.h:221 est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93\nModules linked in:\nCPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)}\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025\n RIP: 0010:__seqprop_assert include/linux/seqlock.h:221 [inline]\n RIP: 0010:est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93\nCall Trace:\n <TASK>\n call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747\n expire_timers kernel/time/timer.c:1798 [inline]\n __run_timers kernel/time/timer.c:2372 [inline]\n __run_timer_base+0x648/0x970 kernel/time/timer.c:2384\n run_timer_base kernel/time/timer.c:2393 [inline]\n run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403\n handle_softirqs+0x22c/0x710 kernel/softirq.c:579\n __do_softirq kernel/softirq.c:613 [inline]\n run_ktimerd+0xcf/0x190 kernel/softirq.c:1043\n smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160\n kthread+0x70e/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n </TASK>"
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet_sched: gen_estimator: corrección de est_timer() frente a CONFIG_PREEMPT_RT=y\n\nsyzbot informó una ADVERTENCIA en est_timer() [1]\n\nEl problema aquí es que con CONFIG_PREEMPT_RT=y, las devoluciones de llamada del temporizador pueden ser expropiadas.\n\nSe adoptan preempt_disable_nested()/preempt_enable_nested() para solucionar esto.\n\n[1]\n ADVERTENCIA: CPU: 0 PID: 16 en ./include/linux/seqlock.h:221 __seqprop_assert include/linux/seqlock.h:221 [en línea]\n ADVERTENCIA: CPU: 0 PID: 16 en ./include/linux/seqlock.h:221 est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93\nMódulos enlazados:\nCPU: 0 UID: 0 PID: 16 Comm: ktimers/0 No contaminado syzkaller #0 PREEMPT_{RT,(full)}\nNombre del hardware: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025\n RIP: 0010:__seqprop_assert include/linux/seqlock.h:221 [en línea]\n RIP: 0010:est_timer+0x6dc/0x9f0 net/core/gen_estimator.c:93\nTraza de llamadas:\n <TAREA>\n call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747\n expire_timers kernel/time/timer.c:1798 [en línea]\n __run_timers kernel/time/timer.c:2372 [en línea]\n __run_timer_base+0x648/0x970 kernel/time/timer.c:2384\n run_timer_base kernel/time/timer.c:2393 [en línea]\n run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403\n handle_softirqs+0x22c/0x710 kernel/softirq.c:579\n __do_softirq kernel/softirq.c:613 [en línea]\n run_ktimerd+0xcf/0x190 kernel/softirq.c:1043\n smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160\n kthread+0x70e/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n </TAREA>"
}
],
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"affectedData": [
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"programFiles": [
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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],
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},
{
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},
{
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},
{
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},
{
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"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
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{
"source": "[email protected]",
"type": "Primary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
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},
{
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"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
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"impactScore": 3.6
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-01-14T19:29:22.173838Z",
"id": "CVE-2025-39900",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
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}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"weaknesses": [
{
"source": "[email protected]",
"type": "Primary",
"description": [
{
"lang": "en",
"value": "NVD-CWE-noinfo"
}
]
}
],
"configurations": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
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