# CVE-2021-28690: Security feature bypass in xen

> Attackers can bypass TSX Async Abort mitigations after S3 suspend if TSX is disabled via non-default settings, exposing systems to speculative execution attacks.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2021-28690, DEBIAN-CVE-2021-28690, GHSA-7qwx-5h4j-5c9w, UBUNTU-CVE-2021-28690

## What is CVE-2021-28690?

CVE-2021-28690 is a medium-severity vulnerability in Xen Xen, published on 29 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

x86: TSX Async Abort protections not restored after S3 This issue relates to the TSX Async Abort speculative security vulnerability. Please see https://xenbits.xen.org/xsa/advisory-305.html for details. Mitigating TAA by disabling TSX (the default and preferred option) requires selecting a non-default setting in MSR_TSX_CTRL. This setting isn't restored after S3 suspend.

## Which versions are affected by CVE-2021-28690?

It affects 1 product.


Products: Xen Xen.

## How do I fix CVE-2021-28690?

Apply the vendor's patch.

## Is CVE-2021-28690 being exploited?

There is no known exploitation of CVE-2021-28690 in the wild and no public exploit code.

## Other vulnerabilities in Xen Xen

- [CVE-2017-10912](https://insights.sbomify.com/CVE-2017-10912/): Privilege escalation in n/a (critical 10.0)
- [CVE-2017-10918](https://insights.sbomify.com/CVE-2017-10918/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10920](https://insights.sbomify.com/CVE-2017-10920/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10921](https://insights.sbomify.com/CVE-2017-10921/): Memory corruption in n/a (critical 10.0)
- [CVE-2025-27466](https://insights.sbomify.com/CVE-2025-27466/): Mutiple vulnerabilities in the Viridian interface (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28690 and fix it if it is affected.

What it is: CVE-2021-28690 is a medium-severity vulnerability in Xen Xen, published on 29 Jun 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-28690 in the wild and no public exploit code.

Affected product: Xen Xen. 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-2021-28690/ (Markdown: https://insights.sbomify.com/CVE-2021-28690/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28690
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28690
- OSV: https://osv.dev/vulnerability/CVE-2021-28690

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28690/
Summaries are generated and may contain mistakes; the official description above is the record.