# CVE-2021-27738: Improper Access Control to Streaming Coordinator & SSRF

> Unauthenticated attackers can access streaming coordinator endpoints to modify cube assignments and replica sets, potentially enabling limited SSRF.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Jan 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-wrx7-qgmj-mf2q

## What is CVE-2021-27738?

CVE-2021-27738 is a high-severity missing authorization vulnerability in Apache Kylin, published on 6 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

All request mappings in `StreamingCoordinatorController.java` handling `/kylin/api/streaming_coordinator/*` REST API endpoints did not include any security checks, which allowed an unauthenticated user to issue arbitrary requests, such as assigning/unassigning of streaming cubes, creation/modification and deletion of replica sets, to the Kylin Coordinator. For endpoints accepting node details in HTTP message body, unauthenticated (but limited) server-side request forgery (SSRF) can be achieved. This issue affects Apache Kylin Apache Kylin 3 versions prior to 3.1.2.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2021-27738?

2 open source packages ship an affected version, including org.apache.kylin:kylin. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.apache.kylin:kylin` | Maven | All versions | 3.1.3 |
| `org.apache.kylin:kylin` | Maven | All versions | 3.1.3 |

Products: Apache Kylin.

## How do I fix CVE-2021-27738?

Upgrade org.apache.kylin:kylin to 3.1.3 or later.

## Is CVE-2021-27738 being exploited?

There is no known exploitation of CVE-2021-27738 in the wild and no public exploit code.

## Other vulnerabilities in Apache Kylin

- [CVE-2020-1956](https://insights.sbomify.com/CVE-2020-1956/): Apache Kylin OS Command Injection (high 8.8, exploited in the wild)
- [CVE-2026-62390](https://insights.sbomify.com/CVE-2026-62390/): Apache Kylin: SQL Injection Vulnerability in Catalog Cache Refresh API (critical 9.8)
- [CVE-2022-44621](https://insights.sbomify.com/CVE-2022-44621/): Apache Kylin: Command injection by Diagnosis Controller (critical 9.8)
- [CVE-2022-24697](https://insights.sbomify.com/CVE-2022-24697/): Apache Kylin vulnerable to remote code execution (critical 9.8)
- [CVE-2021-31522](https://insights.sbomify.com/CVE-2021-31522/): Apache Kylin unsafe class loading (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-27738 and fix it if it is affected.

What it is: CVE-2021-27738 is a high-severity missing authorization vulnerability in Apache Kylin, published on 6 Jan 2022. 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-2021-27738 in the wild and no public exploit code.

Affected packages and fixed versions:
- org.apache.kylin:kylin (Maven): affected all versions; fixed in 3.1.3
- org.apache.kylin:kylin (Maven): affected all versions; fixed in 3.1.3

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-2021-27738/ (Markdown: https://insights.sbomify.com/CVE-2021-27738/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-27738
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-27738
- OSV: https://osv.dev/vulnerability/CVE-2021-27738

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-27738/
Summaries are generated and may contain mistakes; the official description above is the record.