---
cve: "CVE-2021-21249"
severity: "CRITICAL"
cvss: 9.6
epss: "2.9%"
vendor: "theonedev"
kev: false
exploited: false
published: "2021-01-15 20:10:31"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T00:23:03+02:00"
---

# CVE-2021-21249

> 9.6 CRITICAL · 🧪 PoC

## Beschreibung

OneDev is an all-in-one devops platform. In OneDev before version 4.0.3, there is an issue involving YAML parsing which can lead to post-auth remote code execution. In order to parse and process YAML files, OneDev uses SnakeYaml which by default (when not using `SafeConstructor`) allows the instantiation of arbitrary classes. We can leverage that to run arbitrary code by instantiating classes such as `javax.script.ScriptEngineManager` and using `URLClassLoader` to load the script engine provider, resulting in the instantiation of a user controlled class. For a full example refer to the referenced GHSA. This issue was addressed in 4.0.3 by only allowing certain known classes to be deserialized

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 4bd71941974a1b077e955616d7ba3da6fd21670c (Commit)
- d6fc4212b1ac1e9bbe3ce444e95f9af1e3ab8b66 (Commit)

## Referenzen

- <https://github.com/theonedev/onedev/security/advisories/GHSA-7xhq-m2q9-6hpm>
- <https://github.com/theonedev/onedev/commit/d6fc4212b1ac1e9bbe3ce444e95f9af1e3ab8b66>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2021-21249) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_