# CVE-2026-31470: virt: tdx-guest: Fix handling of host controlled 'quote' buffer length

> A malicious host can leak kernel memory to guest userspace in Intel TDX environments by manipulating quote buffer lengths, potentially crossing container boundaries.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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:** 22 Apr 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-31470, DEBIAN-CVE-2026-31470, GHSA-86qf-jwhq-f4jq, ROOT-OS-DEBIAN-13-CVE-2026-31470, ROOT-OS-UBUNTU-2404-CVE-2026-31470, UBUNTU-CVE-2026-31470

## What is CVE-2026-31470?

CVE-2026-31470 is a high-severity vulnerability in Linux kernel, published on 22 Apr 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:

virt: tdx-guest: Fix handling of host controlled 'quote' buffer length

Validate host controlled value `quote_buf->out_len` that determines how
many bytes of the quote are copied out to guest userspace. In TDX
environments with remote attestation, quotes are not considered private,
and can be forwarded to an attestation server.

Catch scenarios where the host specifies a response length larger than
the guest's allocation, or otherwise races modifying the response while
the guest consumes it.

This prevents contents beyond the pages allocated for `quote_buf`
(up to TSM_REPORT_OUTBLOB_MAX) from being read out to guest userspace,
and possibly forwarded in attestation requests.

Recall that some deployments want per-container configs-tsm-report
interfaces, so the leak may cross container protection boundaries, not
just local root.

Weakness: CWE-787 (Out-of-bounds Write), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-31470?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31470?

Apply the vendor's patch.

## Is CVE-2026-31470 being exploited?

There is no known exploitation of CVE-2026-31470 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31470 and fix it if it is affected.

What it is: CVE-2026-31470 is a high-severity vulnerability in Linux kernel, published on 22 Apr 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-2026-31470 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-31470/ (Markdown: https://insights.sbomify.com/CVE-2026-31470/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31470
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31470
- OSV: https://osv.dev/vulnerability/CVE-2026-31470

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31470/
Summaries are generated and may contain mistakes; the official description above is the record.