Security assessments indicate that CVE-2021-21411 presents a notable risk, potentially requiring prompt mitigation.
Status: Modified
Last updated: 🕠 21 Nov 2024, 05:48 UTC
Originally published on: 🕘 26 Mar 2021, 21:15 UTC
Time between publication and last update: 1335 days
CVSS Release: version 3
security-advisories@github.com
Secondary
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
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.
The exploitability of CVE-2021-21411 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
The exploitability of CVE-2021-21411 is influenced by multiple factors. Security teams should analyze system configurations and apply appropriate countermeasures to mitigate threats.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2021-21411, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2021-21411, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
The EPSS score estimates the probability that this vulnerability will be exploited in the near future.
EPSS Score: 0.077% (probability of exploit)
EPSS Percentile: 36.58%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 63.42% of others.
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