# CVE-2021-27635: XML external entity in SAP NetWeaver AS for JAVA

> An authenticated administrator can exploit missing XML validation to read arbitrary files or crash the system via a crafted XML file.

- **Severity:** Critical 9.0 (`CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-353p-c73g-8fwc

## What is CVE-2021-27635?

CVE-2021-27635 is a critical vulnerability in SAP NetWeaver AS for JAVA, published on 9 Jun 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

SAP NetWeaver AS for JAVA, versions - 7.20, 7.30, 7.31, 7.40, 7.50, allows an attacker authenticated as an administrator to connect over a network and submit a specially crafted XML file in the application because of missing XML Validation, this vulnerability enables attacker to fully compromise confidentiality by allowing them to read any file on the filesystem or fully compromise availability by causing the system to crash. The attack cannot be used to change any data so that there is no compromise as to integrity.

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

## Which versions are affected by CVE-2021-27635?

It affects 1 product.


Products: Sap Netweaver Application Server for Java.

## How do I fix CVE-2021-27635?

No fix has been published for CVE-2021-27635 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-27635 being exploited?

There is no known exploitation of CVE-2021-27635 in the wild and no public exploit code.

## Other vulnerabilities in SAP NetWeaver AS for JAVA

- [CVE-2023-23857](https://insights.sbomify.com/CVE-2023-23857/): Improper Access Control in SAP NetWeaver AS for Java (critical 9.9)
- [CVE-2023-0017](https://insights.sbomify.com/CVE-2023-0017/): Improper access control in SAP NetWeaver AS for Java (critical 9.4)
- [CVE-2023-30744](https://insights.sbomify.com/CVE-2023-30744/): Improper access control during application start-up in SAP AS NetWeaver JAVA. (high 8.2)
- [CVE-2022-27669](https://insights.sbomify.com/CVE-2022-27669/): Missing authorization in SAP NetWeaver Application Server for Java (high 7.5)
- [CVE-2021-27621](https://insights.sbomify.com/CVE-2021-27621/): Information disclosure in SAP NetWeaver AS for Java (UserAdmin) (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27635 and fix it if it is affected.

What it is: CVE-2021-27635 is a critical vulnerability in SAP NetWeaver AS for JAVA, published on 9 Jun 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-27635 in the wild and no public exploit code.

Affected product: SAP NetWeaver AS for JAVA. 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-2021-27635/ (Markdown: https://insights.sbomify.com/CVE-2021-27635/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27635
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27635
- OSV: https://osv.dev/vulnerability/CVE-2021-27635

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27635/
Summaries are generated and may contain mistakes; the official description above is the record.