# CVE-2026-90002: ftrace: Take trace_array reference before accessing its ftrace_ops

> A race condition in the Linux kernel ftrace subsystem allows a use-after-free, leading to a kernel crash and denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-101693, BELL-CVE-2026-90002, DEBIAN-CVE-2026-90002, GHSA-hxw4-9m57-prf4, UBUNTU-CVE-2026-90002

## What is CVE-2026-90002?

CVE-2026-90002 is a high-severity use after free vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

ftrace: Take trace_array reference before accessing its ftrace_ops

The trace instance files set_ftrace_filter and set_ftrace_notrace was
updated to work with specific trace instances (trace_arrays). The issue is
that when these files are opened, there is a small race window where it
will use the ftrace_ops from the inode->private pointer to get a reference
to the trace_array and then take its reference. The problem is that the
ftrace_ops itself could be freed. If the rmdir on the instance happens at
the same time the set_ftrace_filter file is opened, the rmdir could have
also freed the ftrace_ops and referencing it will cause a use-after-free
bug and crash the kernel.

Instead, pass in the trace_array as the file private data (NULL for the
top level instance), and then pass both the trace_array and the ftrace_ops
to the ftrace_regex_open() function. If the trace_array is NULL, then it
just uses the ftrace_ops without the need to take its reference (like
normal). If the ftrace_ops is NULL, that is only the case for the top
level instance and the global_ops can be used.

This allows the trace_array to have its reference incremented before
touching the ftrace_ops that could also be freed when the instance is.

## Which versions are affected by CVE-2026-90002?


## How do I fix CVE-2026-90002?

Apply the vendor's patch.

## Is CVE-2026-90002 being exploited?

There is no known exploitation of CVE-2026-90002 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90002 and fix it if it is affected.

What it is: CVE-2026-90002 is a high-severity use after free vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90002 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-90002/ (Markdown: https://insights.sbomify.com/CVE-2026-90002/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90002
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90002
- OSV: https://osv.dev/vulnerability/CVE-2026-90002

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90002/
Summaries are generated and may contain mistakes; the official description above is the record.