# CVE-2021-21266: XXE vulnerability in OpenHAB

> Attackers on the same network can exploit XXE vulnerabilities in openHAB add-ons to read internal files from the system.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/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:** No
- **Published:** 1 Feb 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-r2hc-pmr7-4c9r

## What is CVE-2021-21266?

CVE-2021-21266 is a medium-severity vulnerability in openhab-addons, published on 1 Feb 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

openHAB is a vendor and technology agnostic open source automation software for your home. In openHAB before versions 2.5.12 and 3.0.1 the XML external entity (XXE) attack allows attackers in the same network as the openHAB instance to retrieve internal information like the content of files from the file system. Responses to SSDP requests can be especially malicious. All add-ons that use SAX or JAXB parsing of externally received XML are potentially subject to this kind of attack. In openHAB, the following add-ons are potentially impacted: AvmFritz, BoseSoundtouch, DenonMarantz, DLinkSmarthome, Enigma2, FmiWeather, FSInternetRadio, Gce, Homematic, HPPrinter, IHC, Insteon, Onkyo, Roku, SamsungTV, Sonos, Roku, Tellstick, TR064, UPnPControl, Vitotronic, Wemo, YamahaReceiver and XPath Tranformation. The vulnerabilities have been fixed in versions 2.5.12 and 3.0.1 by a more strict configuration of the used XML parser.

Weakness: CWE-611 (Improper Restriction of XML External Entity Reference)

## Which versions are affected by CVE-2021-21266?

It affects 1 product.


Products: Openhab Openhab.

## How do I fix CVE-2021-21266?

No fix has been published for CVE-2021-21266 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21266 being exploited?

There is no known exploitation of CVE-2021-21266 in the wild and no public exploit code.

## Other vulnerabilities in openhab-addons

- [CVE-2024-42469](https://insights.sbomify.com/CVE-2024-42469/): CometVisu Backend for openHAB affected by RCE through path traversal (critical 9.8)
- [CVE-2020-5242](https://insights.sbomify.com/CVE-2020-5242/): openHAB exec add-ons allow remote arbitrary command execution (high 7.7)
- [CVE-2024-42470](https://insights.sbomify.com/CVE-2024-42470/): CometVisu Backend for openHAB has a sensitive information disclosure vulnerability (medium 6.5)
- [CVE-2024-42468](https://insights.sbomify.com/CVE-2024-42468/): Path traversal (CometVisu) (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21266 and fix it if it is affected.

What it is: CVE-2021-21266 is a medium-severity vulnerability in openhab-addons, published on 1 Feb 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-2021-21266 in the wild and no public exploit code.

Affected product: openhab-addons. 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-2021-21266/ (Markdown: https://insights.sbomify.com/CVE-2021-21266/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21266
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21266
- OSV: https://osv.dev/vulnerability/CVE-2021-21266

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21266/
Summaries are generated and may contain mistakes; the official description above is the record.