# CVE-2021-23856: Reflected Cross-Site-Scripting

> An attacker can execute arbitrary scripts on a client's computer via a manipulated URL in the Rexroth IndraMotion web server.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/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:** 4 Oct 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-q4r8-4f4f-m9xf

## What is CVE-2021-23856?

CVE-2021-23856 is a critical cross-site scripting vulnerability in Rexroth IndraMotion MLC L20, L40, published on 4 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The web server is vulnerable to reflected XSS and therefore an attacker might be able to execute scripts on a client’s computer by sending the client a manipulated URL.

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

## Which versions are affected by CVE-2021-23856?

It affects 2 products.


Products: Bosch Rexroth Indramotion Mlc L20 Firmware, Bosch Rexroth Indramotion Mlc L40 Firmware.

## How do I fix CVE-2021-23856?

No fix has been published for CVE-2021-23856 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-23856 being exploited?

There is no known exploitation of CVE-2021-23856 in the wild and no public exploit code.

## Other vulnerabilities in Rexroth IndraMotion MLC L20, L40

- [CVE-2021-23857](https://insights.sbomify.com/CVE-2021-23857/): Login with hash (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-23856 and fix it if it is affected.

What it is: CVE-2021-23856 is a critical cross-site scripting vulnerability in Rexroth IndraMotion MLC L20, L40, published on 4 Oct 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-2021-23856 in the wild and no public exploit code.

Affected product: Rexroth IndraMotion MLC L20, L40. 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-2021-23856/ (Markdown: https://insights.sbomify.com/CVE-2021-23856/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-23856
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-23856
- OSV: https://osv.dev/vulnerability/CVE-2021-23856

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-23856/
Summaries are generated and may contain mistakes; the official description above is the record.