# CVE-2026-92505: iommu/amd: Fix undefined behavior in devid_write debugfs function

> A local attacker with debugfs access can trigger undefined behavior in the AMD IOMMU driver, potentially causing a system crash.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-92505, DEBIAN-CVE-2026-92505, GHSA-2mxc-qwhf-8gfr, UBUNTU-CVE-2026-92505

## What is CVE-2026-92505?

CVE-2026-92505 is a vulnerability in Linux, published on 17 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:

iommu/amd: Fix undefined behavior in devid_write debugfs function

When for_each_pci_segment() loop completes without finding a matching
segment, the pci_seg pointer is not NULL but points to an invalid memory
location (the list head). Accessing pci_seg->id after the loop causes
undefined behavior.

Fix this by handling the successful case inside the loop and returning
-EINVAL after the loop if no matching segment is found.

## Which versions are affected by CVE-2026-92505?


## How do I fix CVE-2026-92505?

Apply the vendor's patch.

## Is CVE-2026-92505 being exploited?

There is no known exploitation of CVE-2026-92505 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-92505 and fix it if it is affected.

What it is: CVE-2026-92505 is a vulnerability in Linux, published on 17 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-2026-92505 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-2026-92505/ (Markdown: https://insights.sbomify.com/CVE-2026-92505/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-92505
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-92505
- OSV: https://osv.dev/vulnerability/CVE-2026-92505

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-92505/
Summaries are generated and may contain mistakes; the official description above is the record.