Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
High
Attack Vector
Network
0

CVE-2021-21411

Disclosure Date: March 26, 2021
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

OAuth2-Proxy is an open source reverse proxy that provides authentication with Google, Github or other providers. The --gitlab-group flag for group-based authorization in the GitLab provider stopped working in the v7.0.0 release. Regardless of the flag settings, authorization wasn’t restricted. Additionally, any authenticated users had whichever groups were set in --gitlab-group added to the new X-Forwarded-Groups header to the upstream application. While adding GitLab project based authorization support in #630, a bug was introduced where the user session’s groups field was populated with the --gitlab-group config entries instead of pulling the individual user’s group membership from the GitLab Userinfo endpoint. When the session groups where compared against the allowed groups for authorization, they matched improperly (since both lists were populated with the same data) so authorization was allowed. This impacts GitLab Provider users who relies on group membership for authorization restrictions. Any authenticated users in your GitLab environment can access your applications regardless of --gitlab-group membership restrictions. This is patched in v7.1.0. There is no workaround for the Group membership bug. But --gitlab-project can be set to use Project membership as the authorization checks instead of groups; it is not broken.

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CVSS V3 Severity and Metrics
Base Score:
5.5 Medium
Impact Score:
2.7
Exploitability Score:
2.3
Vector:
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
Attack Vector (AV):
Network
Attack Complexity (AC):
Low
Privileges Required (PR):
High
User Interaction (UI):
None
Scope (S):
Changed
Confidentiality (C):
Low
Integrity (I):
Low
Availability (A):
None

General Information

Products

Weaknesses

Technical Analysis