CVE-2026-90066: Linux kernel · samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in cf839636911d8313f3ecd098329fd0b96499e4cf : update Linux kernel when convenient.
Data as of 30 Oct 2026, 13:03 UTC
Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD
Thin evidence
One scorer or none- Patch
- Available – fixed in cf839636911d8313f3ecd098329fd0b96499e4cf, 626614df9080d7052fbe24dc90b5434717ab7a9f, 6727b7618f49401acf373fa3ec5712e2ec52e5cf +3
Exploitation evidence
Disclosed: evidence found.
CVE published 17 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
AI-suggested
A fix is available and has been applied in the Linux kernel commits identified by hashes cf839636911d8313f3ecd098329fd0b96499e4cf, 626614df9080d7052fbe24dc90b5434717ab7a9f, 6727b7618f49401acf373fa3ec5712e2ec52e5cf, 02866f063062dcc5686445c738be003de9787250, 98b7b2a29ae87937aa02ab9391543ef8c602cd94, and 7a96b9f6d5ba23dbce66c8a4a242effd4c01a830. Users should update to a fixed kernel version containing these commits to remediate the issue.
Description
A vulnerability in the Linux kernel's ftrace module (version 5.16) involves improper handling of the return value from kthread_run(). The function ftrace_direct_multi_init() does not check if kthread_run() returns an error pointer (ERR_PTR), leading to a scenario where the module loads with an invalid task pointer. On module unload, this causes ftrace_direct_multi_exit() to pass the error pointer to kthread_stop(), resulting in a null-pointer dereference. The issue has been fixed by adding an IS_ERR() check and proper error handling.
References
- git.kernel.org/stable/c/02866f063062dcc5686445c738be003de9787250 (opens in a new tab)
- git.kernel.org/stable/c/7a96b9f6d5ba23dbce66c8a4a242effd4c01a830 (opens in a new tab)
- git.kernel.org/stable/c/98b7b2a29ae87937aa02ab9391543ef8c602cd94 (opens in a new tab)
- git.kernel.org/stable/c/626614df9080d7052fbe24dc90b5434717ab7a9f (opens in a new tab)
- git.kernel.org/stable/c/cf839636911d8313f3ecd098329fd0b96499e4cf (opens in a new tab)
- git.kernel.org/stable/c/6727b7618f49401acf373fa3ec5712e2ec52e5cf (opens in a new tab)