# CVE-2026-98687: thunderbolt: Reject oversized XDomain properties responses

> A malicious Thunderbolt peer can trigger a heap out-of-bounds read in the Linux kernel, potentially leaking memory or causing a crash.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-108953, BELL-CVE-2026-98687, DEBIAN-CVE-2026-98687, GHSA-rq3j-rw4p-w59w, UBUNTU-CVE-2026-98687

## What is CVE-2026-98687?

CVE-2026-98687 is a memory corruption vulnerability in Linux, published on 18 Oct 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:

thunderbolt: Reject oversized XDomain properties responses

tb_xdp_properties_request() allocates room for 45 data dwords in its
252-byte response buffer.  The XDomain length field is six bits wide,
however, and a malicious peer can set it to 63.  After the fixed response
fields are subtracted, the driver treats this as 48 data dwords.

Commit 322e93448d90 ("thunderbolt: Clamp XDomain response data copy to
allocation size") only bounds the copy against data_len.  If data_len is
at least 48, memcpy() reads 192 bytes from the 180-byte res->data array,
causing a 12-byte heap out-of-bounds read.  Commit 4db2bd2ed478
("thunderbolt: Limit XDomain response copy to actual frame size") limits
the earlier copy but does not constrain this header-derived length.

Reject response data lengths that exceed the allocated source buffer
before copying them into the assembled property block.

## Which versions are affected by CVE-2026-98687?


## How do I fix CVE-2026-98687?

Apply the vendor's patch.

## Is CVE-2026-98687 being exploited?

There is no known exploitation of CVE-2026-98687 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98687 and fix it if it is affected.

What it is: CVE-2026-98687 is a memory corruption vulnerability in Linux, published on 18 Oct 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-2026-98687 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-2026-98687/ (Markdown: https://insights.sbomify.com/CVE-2026-98687/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98687
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98687
- OSV: https://osv.dev/vulnerability/CVE-2026-98687

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98687/
Summaries are generated and may contain mistakes; the official description above is the record.