CVE-2026-98286
Received
Received - Intake
Use-After-Free in Linux Kernel drop_monitor
Vulnerability report for CVE-2026-98286, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-06
Last updated on: 2026-10-06
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
drop_monitor: use timer_shutdown_sync() to prevent timer rearming during teardown
In drop_monitor teardown paths (net_dm_trace_off_set(),
net_dm_hw_monitor_stop(), and error unwind paths in net_dm_trace_on_set()
and net_dm_hw_monitor_start()), per-CPU timers are stopped using
timer_delete_sync() followed by cancel_work_sync().
However, there is a circular dependency between send_timer and
dm_alert_work:
1) sched_send_work() (timer callback) schedules dm_alert_work.
2) send_dm_alert() / net_dm_hw_summary_work() calls reset_per_cpu_data()
or net_dm_hw_reset_per_cpu_data().
3) If memory allocation fails under memory pressure in the reset
function, it re-arms the timer via mod_timer(&data->send_timer, ...).
If dm_alert_work is running concurrently while timer_delete_sync()
executes on another CPU, an allocation failure in the worker will
re-arm the timer after timer_delete_sync() has already returned.
Once cancel_work_sync() completes and module_put() is called, the timer
remains active in the timer wheel. If the module is then unloaded, the
timer will fire and execute sched_send_work() in freed memory,
triggering a kernel panic / use-after-free.
Switch from timer_delete_sync() to timer_shutdown_sync(). This guarantees
that any in-flight timer handler has finished and prevents subsequent
re-arming attempts from running workers from succeeding. When monitoring
is restarted later, timer_setup() is invoked, which cleanly
re-initializes the timer.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | 9398e9c0b1d44eeb700e9e766c02bcc765c82570 |
| Linux | Linux | 9398e9c0b1d44eeb700e9e766c02bcc765c82570 |
| Linux | Linux | 9398e9c0b1d44eeb700e9e766c02bcc765c82570 |
| Linux | Linux | 2514c7ad115e762562c7bdd58bb1ab3425a98245 |
| Linux | Linux | 439b1164da3612ec7e186e1dc314471e7190bfc7 |
| Linux | Linux | 5.10.27 |
| Linux | Linux | 5.11.11 |
| Linux | Linux | 5.12 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
