# CVE-2021-42856: Reflected Cross-site Scripting at DsaDataTest

> Attackers can execute arbitrary scripts in user browsers via the DsaDataTest endpoint due to lack of input validation on the Metric parameter.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 9 Mar 2022
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-4gxc-qfxh-4hf6

## What is CVE-2021-42856?

CVE-2021-42856 is a medium-severity cross-site scripting vulnerability in Aternity SteelCentral AppInternals Dynamic Sampling Agent, published on 9 Mar 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

It was discovered that the /DsaDataTest endpoint is susceptible to Cross-site scripting (XSS) attack. It was noted that the Metric parameter does not have any input checks on the user input that allows an attacker to craft its own malicious payload to trigger a XSS vulnerability.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-42856?

It affects 1 product.


Products: Riverbed Steelcentral Appinternals Dynamic Sampling Agent.

## How do I fix CVE-2021-42856?

No fix has been published for CVE-2021-42856 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-42856 being exploited?

There is no known exploitation of CVE-2021-42856 in the wild and no public exploit code.

## Other vulnerabilities in Aternity SteelCentral AppInternals Dynamic Sampling Agent

- [CVE-2021-42786](https://insights.sbomify.com/CVE-2021-42786/): Remote Code Execution at AgentControllerServlet (critical 9.8)
- [CVE-2021-42854](https://insights.sbomify.com/CVE-2021-42854/): Directory Traversal Read/Write/Delete at PluginServlet (critical 9.8)
- [CVE-2021-42787](https://insights.sbomify.com/CVE-2021-42787/): Directory Traversal Write/Delete/Partial Read at AgentConfigurationServlet (critical 9.4)
- [CVE-2021-42853](https://insights.sbomify.com/CVE-2021-42853/): Directory Traversal Delete/Read at AgentDiagnosticServlet (critical 9.1)
- [CVE-2021-42855](https://insights.sbomify.com/CVE-2021-42855/): Local privilege escalation due to misconfigured write permission on .debug_command.config file (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-42856 and fix it if it is affected.

What it is: CVE-2021-42856 is a medium-severity cross-site scripting vulnerability in Aternity SteelCentral AppInternals Dynamic Sampling Agent, published on 9 Mar 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-42856 in the wild and no public exploit code.

Affected product: Aternity SteelCentral AppInternals Dynamic Sampling Agent. 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-2021-42856/ (Markdown: https://insights.sbomify.com/CVE-2021-42856/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-42856
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-42856
- OSV: https://osv.dev/vulnerability/CVE-2021-42856

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From sbomify Insights: https://insights.sbomify.com/CVE-2021-42856/
Summaries are generated and may contain mistakes; the official description above is the record.