CVE-2021-21249

Severity CVSS v4.0:

Pending analysis

Type:

CWE-502 Deserialization of Untrusted Dat

Publication date:

15/01/2021

Last modified:

26/04/2022

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

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 8.80 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x

8.80

Severity 3.x

HIGH

Vector 2.0

AV:N/AC:L/Au:S/C:P/I:P/A:P CVSS v2.0 Severity and Metrics:

Base Score: 6.50 MEDIUM
Vector: AV:N/AC:L/Au:S/C:P/I:P/A:P

Attack Vector (AV): Network
Attack Complexity (AC): Low
Authentication (Au): Single
Confidentiality (C): Physical
Integrity (I): Physical
Availability (A): Physical