Vulnerability · Published Jan 15, 2021 · Assigned by GitHub_M
CVE-2021-21249Post-Auth Unsafe Yaml deserialization
Critical 9.6
In plain English
A critical-severity injection in onedev from theonedev. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 3.1% (higher than 88% of all known vulnerabilities).
Official description
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
Affected products (as reported)
Weakness: CWE-74 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N