# CVE-2021-32836: Pre-auth unsafe deserialization in ZStack

> Pre-auth unsafe deserialization in ZStack REST API allows attackers to cause denial of service or potentially execute arbitrary code.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Sep 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-gpj5-98pq-4552

## What is CVE-2021-32836?

CVE-2021-32836 is a high-severity unsafe deserialization vulnerability in zstackio zstack, published on 9 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ZStack is open source IaaS(infrastructure as a service) software. In ZStack before versions 3.10.12 and 4.1.6 there is a pre-auth unsafe deserialization vulnerability in the REST API. An attacker in control of the request body will be able to provide both the class name and the data to be deserialized and therefore will be able to instantiate an arbitrary type and assign arbitrary values to its fields. This issue may lead to a Denial Of Service. If a suitable gadget is available, then an attacker may also be able to exploit this vulnerability to gain pre-auth remote code execution. For additional details see the referenced GHSL-2021-087.

Weakness: CWE-502 (Deserialization of Untrusted Data), CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2021-32836?

It affects 1 product.


Products: Zstack Zstack.

## How do I fix CVE-2021-32836?

No fix has been published for CVE-2021-32836 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-32836 being exploited?

There is no known exploitation of CVE-2021-32836 in the wild and no public exploit code.

## Other vulnerabilities in zstackio zstack

- [CVE-2023-46326](https://insights.sbomify.com/CVE-2023-46326/): Information disclosure in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32836 and fix it if it is affected.

What it is: CVE-2021-32836 is a high-severity unsafe deserialization vulnerability in zstackio zstack, published on 9 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-32836 in the wild and no public exploit code.

Affected product: zstackio zstack. 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-2021-32836/ (Markdown: https://insights.sbomify.com/CVE-2021-32836/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32836
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32836
- OSV: https://osv.dev/vulnerability/CVE-2021-32836

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32836/
Summaries are generated and may contain mistakes; the official description above is the record.