# CVE-2026-98728: tpm: fix off-by-four bounds check in tpm2_get_random()

> A local attacker can read stale kernel memory via a truncated TPM response, potentially leaking sensitive data.

- **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:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98728, DEBIAN-CVE-2026-98728, GHSA-m4p2-cqr5-x7cx, UBUNTU-CVE-2026-98728

## What is CVE-2026-98728?

CVE-2026-98728 is a 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:

tpm: fix off-by-four bounds check in tpm2_get_random()

When the response carries the TPM2_ST_SESSIONS tag, tpm2_get_random()
skips the 4-byte parameter size field before locating the random data,
but the bounds check still validates the response length against
TPM_HEADER_SIZE.  A truncated response can pass the check and make
memcpy() read up to 4 bytes past the response end, so stale buffer
contents end up in the caller's random bytes.

Fix this by checking the response length against 'offset', which
already includes the skipped parameter size field.

## Which versions are affected by CVE-2026-98728?


## How do I fix CVE-2026-98728?

Apply the vendor's patch.

## Is CVE-2026-98728 being exploited?

There is no known exploitation of CVE-2026-98728 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98728 and fix it if it is affected.

What it is: CVE-2026-98728 is a 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-2026-98728 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-2026-98728/ (Markdown: https://insights.sbomify.com/CVE-2026-98728/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98728
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98728
- OSV: https://osv.dev/vulnerability/CVE-2026-98728

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98728/
Summaries are generated and may contain mistakes; the official description above is the record.