# CVE-2021-26342: Information disclosure in EPYC™ Processors

> A CPU microcode flaw in AMD EPYC processors may allow disclosure of SEV guest memory contents due to stale TLB translations.

- **Severity:** Low 3.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N`)
- **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:** 11 May 2022
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-wp53-p3r5-cq4w

## What is CVE-2021-26342?

CVE-2021-26342 is a low-severity vulnerability in Amd Epyc 72f3 Firmware, published on 11 May 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In SEV guest VMs, the CPU may fail to flush the Translation Lookaside Buffer (TLB) following a particular sequence of operations that includes creation of a new virtual machine control block (VMCB). The failure to flush the TLB may cause the microcode to use stale TLB translations which may allow for disclosure of SEV guest memory contents. Users of SEV-ES/SEV-SNP guest VMs are not impacted by this vulnerability.

## Which versions are affected by CVE-2021-26342?

It affects 38 products.


Products: Amd Epyc 7001 Firmware, Amd Epyc 7251 Firmware, Amd Epyc 7261 Firmware, Amd Epyc 7281 Firmware, Amd Epyc 72f3 Firmware, Amd Epyc 7301 Firmware, Amd Epyc 7313 Firmware, Amd Epyc 7313p Firmware, Amd Epyc 7343 Firmware, Amd Epyc 7351 Firmware, Amd Epyc 7351p Firmware, Amd Epyc 7371 Firmware, Amd Epyc 7373x Firmware, Amd Epyc 73f3 Firmware, Amd Epyc 7401 Firmware, Amd Epyc 7401p Firmware, Amd Epyc 7413 Firmware, Amd Epyc 7443 Firmware, Amd Epyc 7443p Firmware, Amd Epyc 7451 Firmware and 18 more.

## How do I fix CVE-2021-26342?

Apply the vendor's patch.

## Is CVE-2021-26342 being exploited?

There is no known exploitation of CVE-2021-26342 in the wild and no public exploit code.

## Other vulnerabilities in Amd Epyc 72f3 Firmware

- [CVE-2021-26340](https://insights.sbomify.com/CVE-2021-26340/): A malicious hypervisor in conjunction with an unprivileged attacker process inside an SEV/SEV-ES guest VM may fail to flush the Translation (high 8.4)
- [CVE-2021-26398](https://insights.sbomify.com/CVE-2021-26398/): Memory corruption in 1st Gen EPYC (high 7.8)
- [CVE-2021-26331](https://insights.sbomify.com/CVE-2021-26331/): Code injection in 1st Gen AMD EPYC™ (high 7.8)
- [CVE-2021-26335](https://insights.sbomify.com/CVE-2021-26335/): Code injection in Athlon™ Series (high 7.8)
- [CVE-2023-20578](https://insights.sbomify.com/CVE-2023-20578/): Race condition in AMD EPYC™ 7001 Processors (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-26342 and fix it if it is affected.

What it is: CVE-2021-26342 is a low-severity vulnerability in Amd Epyc 72f3 Firmware, published on 11 May 2022. 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-2021-26342 in the wild and no public exploit code.

Affected product: Amd Epyc 72f3 Firmware. 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-2021-26342/ (Markdown: https://insights.sbomify.com/CVE-2021-26342/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-26342
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-26342
- OSV: https://osv.dev/vulnerability/CVE-2021-26342

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-26342/
Summaries are generated and may contain mistakes; the official description above is the record.