OneDev up to 4.0.2 YAML Parser deserialization

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CVSS Meta Temp Score
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7.2$0-$5k0.09

A vulnerability was found in OneDev up to 4.0.2. It has been declared as critical. Affected by this vulnerability is some unknown processing of the component YAML Parser. The manipulation with an unknown input leads to a privilege escalation vulnerability. The CWE definition for the vulnerability is CWE-502. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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

The weakness was published 01/16/2021. It is possible to read the advisory at github.com. This vulnerability is known as CVE-2021-21249 since 12/22/2020. The exploitation appears to be easy. The attack can be launched remotely. Required for exploitation is a single authentication. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 4.0.3 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.2

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 8.8
NVD Vector: 🔒

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

NVD Base Score: 🔒

Exploitinginfoedit

Class: Privilege escalation
CWE: CWE-502
ATT&CK: Unknown

Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfoedit

Threat: 🔍
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Countermeasuresinfoedit

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: OneDev 4.0.3
Patch: github.com

Timelineinfoedit

12/22/2020 CVE assigned
01/16/2021 +25 days Advisory disclosed
01/16/2021 +0 days VulDB entry created
02/15/2021 +30 days VulDB last update

Sourcesinfoedit

Advisory: github.com
Status: Confirmed
Confirmation: 🔒

CVE: CVE-2021-21249 (🔒)

Entryinfoedit

Created: 01/16/2021 09:27 AM
Updated: 02/15/2021 02:31 AM
Changes: (19) vulnerability_cvss3_nvd_av vulnerability_cvss3_nvd_ac vulnerability_cvss3_nvd_pr vulnerability_cvss3_nvd_ui vulnerability_cvss3_nvd_s vulnerability_cvss3_nvd_c vulnerability_cvss3_nvd_i vulnerability_cvss3_nvd_a vulnerability_cvss2_nvd_av vulnerability_cvss2_nvd_ac vulnerability_cvss2_nvd_au vulnerability_cvss2_nvd_ci vulnerability_cvss2_nvd_ii vulnerability_cvss2_nvd_ai source_cve_cna vulnerability_cvss3_meta_basescore vulnerability_cvss3_meta_tempscore vulnerability_cvss2_nvd_basescore vulnerability_cvss3_nvd_basescore
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