CVE Vulnerability

CVE-2021-21411

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.

5.5 /10

CVSS v2.0 :

V3 Legend

Vector :

Exploitability : 8 / Impact : 4.9

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Confidentiality Impact PARTIAL

Integrity Impact PARTIAL

Availability Impact NONE

Scope

5.5 /10

CVSS v3.0 : MEDIUM

V3 Legend

Vector :

Exploitability : 2.3 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required HIGH

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References
Link Resource
https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-652x-m2gr-hppm Third Party Advisory
https://docs.gitlab.com/ee/user/group/ Third Party Advisory
https://pkg.go.dev/github.com/oauth2-proxy/oauth2-proxy/v7 Product Third Party Advisory
https://github.com/oauth2-proxy/oauth2-proxy/releases/tag/v7.1.0 Release Notes Third Party Advisory
https://github.com/oauth2-proxy/oauth2-proxy/commit/0279fa7dff1752f1710707dbd1ffac839de8bbfc Patch Third Party Advisory
Configurations

Configuration 1

cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:*
Information

Published : 2021-03-26 09:15

Updated : 2021-04-06 12:42

NVD link : CVE-2021-21411

Mitre link : CVE-2021-21411

Products Affected
No products.
CWE
CWE-863