CVE-2021-21249
In your normal cycle
Critical by CVSS (9.6), but no sign of active exploitation.
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
Scoring
| CVSS | 9.6 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N |
| EPSS | 3.06% — more likely to be exploited than 87% of all CVEs |
| Weakness | CWE-74 |
| On CISA KEV | no |
| Public exploit | none known |
| Published | 2021-01-15 |
| Last modified | 2026-06-17 |
Affected (1)
| Vendor | Product |
|---|---|
| onedev project | onedev |
References
- https://github.com/theonedev/onedev/commit/d6fc4212b1ac1e9bbe3ce444e95f9af1e3ab8b66
- https://github.com/theonedev/onedev/security/advisories/GHSA-7xhq-m2q9-6hpm
- https://github.com/theonedev/onedev/commit/d6fc4212b1ac1e9bbe3ce444e95f9af1e3ab8b66
- https://github.com/theonedev/onedev/security/advisories/GHSA-7xhq-m2q9-6hpm
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