# CVE-2021-27852: Checkbox Survey Deserialization of Untrusted Data

> An unauthenticated remote attacker can execute arbitrary code via unsafe deserialization in Checkbox Survey.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 11 Apr 2022 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 May 2021
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-xrx4-vq84-23w6

## What is CVE-2021-27852?

CVE-2021-27852 is a critical unsafe deserialization vulnerability in Checkbox Survey, published on 27 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Deserialization of Untrusted Data vulnerability in CheckboxWeb.dll of Checkbox Survey allows an unauthenticated remote attacker to execute arbitrary code. This issue affects: Checkbox Survey versions prior to 7.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2021-27852?

It affects 1 product.


Products: Checkbox Survey.

## How do I fix CVE-2021-27852?

No fix has been published for CVE-2021-27852 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 2 May 2022.

## Is CVE-2021-27852 being exploited?

Yes. Attackers have exploited CVE-2021-27852 in the wild since at least 11 Apr 2022.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27852 and fix it if it is affected.

What it is: CVE-2021-27852 is a critical unsafe deserialization vulnerability in Checkbox Survey, published on 27 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2021-27852 in the wild since at least 11 Apr 2022.

Affected product: Checkbox Survey. 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-2021-27852/ (Markdown: https://insights.sbomify.com/CVE-2021-27852/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27852
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27852
- OSV: https://osv.dev/vulnerability/CVE-2021-27852

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27852/
Summaries are generated and may contain mistakes; the official description above is the record.