# samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify

CVE record · `CVE-2026-90066`

- **Identifiers:** `CVE-2026-90066`
- **State:** Confirmed
- **Severity:** No CVSS score
- **Critical:** No
- **CNA:** Linux
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 17 Sept 2026
- **Updated:** 30 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 17 Sept 2026, 16:05 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

## Affected products, as the CNA wrote them

- Vendor: Linux. Product: Linux.
  - affected: `e1067a07cfbc5a36abad3752fafe4c79e06db1bb to before 02866f063062dcc5686445c738be003de9787250` (git)
  - affected: `e1067a07cfbc5a36abad3752fafe4c79e06db1bb to before 7a96b9f6d5ba23dbce66c8a4a242effd4c01a830` (git)
  - affected: `e1067a07cfbc5a36abad3752fafe4c79e06db1bb to before 98b7b2a29ae87937aa02ab9391543ef8c602cd94` (git)
  - affected: `e1067a07cfbc5a36abad3752fafe4c79e06db1bb to before 626614df9080d7052fbe24dc90b5434717ab7a9f` (git)
  - affected: `e1067a07cfbc5a36abad3752fafe4c79e06db1bb to before cf839636911d8313f3ecd098329fd0b96499e4cf` (git)
  - affected: `e1067a07cfbc5a36abad3752fafe4c79e06db1bb to before 6727b7618f49401acf373fa3ec5712e2ec52e5cf` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `5.16`
  - unaffected: `before 5.16` (semver)
  - unaffected: `6.1.191 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.157 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.110 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.52 to 6.18.*, inclusive` (semver)
  - unaffected: `7.2.6 to 7.2.*, inclusive` (semver)
  - unaffected: `7.3 to *, inclusive` (original_commit_for_fix)
  - Other versions: affected

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The Linux kernel's ftrace-direct-multi-modify sample module, from 5.16 until fixed, can dereference a null pointer on unload if its kthread failed to start during load. The source gives few details on attacker access. Upgrade to 6.1.191, 6.6.157, 6.12.110, 6.18.52, or a later release in those series.

Written 12 Nov 2026.

## Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

## Severity and exploitation

No source has published a CVSS score for this record yet.

- **CISA KEV:** Not listed.
- **EPSS:** 0.0021, the 10th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the CVE Program, published 17 Sept 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-90066](https://www.cve.org/CVERecord?id=CVE-2026-90066)
- [NVD: CVE-2026-90066](https://nvd.nist.gov/vuln/detail/CVE-2026-90066)

### References from the CNA

- <https://git.kernel.org/stable/c/02866f063062dcc5686445c738be003de9787250>
- <https://git.kernel.org/stable/c/7a96b9f6d5ba23dbce66c8a4a242effd4c01a830>
- <https://git.kernel.org/stable/c/98b7b2a29ae87937aa02ab9391543ef8c602cd94>
- <https://git.kernel.org/stable/c/626614df9080d7052fbe24dc90b5434717ab7a9f>
- <https://git.kernel.org/stable/c/cf839636911d8313f3ecd098329fd0b96499e4cf>
- <https://git.kernel.org/stable/c/6727b7618f49401acf373fa3ec5712e2ec52e5cf>

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.

## Check whether this affects you

This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2026-90066>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-90066/>. Everything for agents: <https://agentprime.io/llms.txt>.