Is CVE-2021-21249 actively exploited?

No active exploitation of CVE-2021-21249 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21249 be exploited remotely?

Yes. CVE-2021-21249 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21249?

CVE-2021-21249 has a CVSS score of 8.8 (HIGH).

HOME VULNERABILITIESCVE-2021-21249

HIGH

CVE-2021-21249

CWE-74Published: January 15, 2021· Updated: Jun 17, 2026

8.8

CVSS v3.1

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

NVD Source

Technical Analysis

CVE-2021-21249 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.