# CVE-2026-74585: thunderbolt: Bound the DROM dual link port number before indexing sw->ports

> A malicious Thunderbolt device can trigger an out-of-bounds write in the Linux kernel, potentially leading to code execution or privilege escalation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Aug 2026
- **Updated:** 22 Aug 2026
- **Also known as:** BELL-CVE-2026-74585, DEBIAN-CVE-2026-74585, GHSA-2wmm-p327-9hx6, UBUNTU-CVE-2026-74585

## What is CVE-2026-74585?

CVE-2026-74585 is a memory corruption vulnerability in Linux, published on 22 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

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

thunderbolt: Bound the DROM dual link port number before indexing sw->ports

tb_drom_parse_entry_port() validates the device-supplied header->index
against sw->config.max_port_number before indexing sw->ports[], but the
sibling field entry->dual_link_port_nr -- a 6-bit value also read from
the DROM -- indexes the same array with no such check. A malicious or
malformed Thunderbolt device can set dual_link_port_nr beyond the
allocated sw->ports[] (max_port_number + 1 entries), producing an
out-of-bounds tb_port pointer that is stored and later dereferenced.

Reject a port entry whose dual_link_port_nr exceeds max_port_number,
the same bound already applied to header->index.

## Which versions are affected by CVE-2026-74585?


## How do I fix CVE-2026-74585?

Apply the vendor's patch.

## Is CVE-2026-74585 being exploited?

There is no known exploitation of CVE-2026-74585 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74585 and fix it if it is affected.

What it is: CVE-2026-74585 is a memory corruption vulnerability in Linux, published on 22 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-74585 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-2026-74585/ (Markdown: https://insights.sbomify.com/CVE-2026-74585/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74585
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74585
- OSV: https://osv.dev/vulnerability/CVE-2026-74585

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74585/
Summaries are generated and may contain mistakes; the official description above is the record.