CVE-2021-41230: Incorrect authorization in github.com/pomerium/pomerium
Summary
CVE-2021-41230: Incorrect authorization in github.com/pomerium/pomerium. Affects github.com/pomerium/pomerium versions < 0.15.6. Fixed in 0.15.6. How to fix ↓
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Background
Pomerium is an open source identity-aware access proxy. It acts as a reverse proxy, allowing secure access to internal applications based on user identity and access policies. It provides features like single sign-on (SSO) and access control for web applications. The vulnerability affects the way Pomerium handles changes to the OpenID Connect (OIDC) claims of a user after initial login. When using the allowed_idp_claims feature as part of policy evaluation, changes to a user's claims are not reflected, leading to incorrect authorization decisions. Pomerium versions prior to 0.15.6 are affected by this vulnerability.
Vulnerability Detail
The vulnerability arises from the failure of Pomerium to update policy evaluation when a user's OIDC claims are modified after initial login. This can result in incorrect authorization decisions being made by Pomerium. The allowed_idp_claims feature, which is used to specify the required claims from the identity provider (IDP), is impacted by this issue. If a user's claims are changed, Pomerium may not re-evaluate the policy based on the updated claims, potentially allowing unauthorized access to protected resources. This vulnerability can be exploited by an attacker who can modify the claims of a user authenticated through an IDP.
How To Fix
Latest published version: v0.33.4 as of 22 Oct 2026
go get github.com/pomerium/pomerium@v0.33.4Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.15.6
This is the first release that contains the fix.
go get github.com/pomerium/pomerium@v0.15.6Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There is no specific workaround mentioned for this vulnerability. However, as a general best practice, it is recommended to regularly update Pomerium to the latest version and follow the upgrade instructions provided by the project. Additionally, ensuring that the databroker service is cleared or restarted when making changes to OIDC claims can help mitigate the impact of this vulnerability.
Conclusion
The vulnerability in Pomerium allows for incorrect authorization decisions when using the allowed_idp_claims feature. Upgrading to Pomerium version 0.15.6 or later and clearing the databroker service can fix this vulnerability. It is important to regularly update Pomerium and follow best practices for secure configuration. For further support on vulnerability remediation, contact DevNack.com.
See every vulnerability recorded for github.com/pomerium/pomerium →
FAQ
Pomerium is an open source identity-aware access proxy that provides secure access to internal applications based on user identity and access policies. It offers features like single sign-on (SSO) and access control for web applications.
The allowed_idp_claims feature in Pomerium allows specifying the required claims from the identity provider (IDP) for policy evaluation. It ensures that only users with the specified claims are granted access to protected resources.
This vulnerability in Pomerium can lead to incorrect authorization decisions. If a user's OIDC claims are modified after initial login and the allowed_idp_claims feature is used in policy evaluation, Pomerium may not re-evaluate the policy based on the updated claims. This can potentially allow unauthorized access to protected resources.
To fix this vulnerability, it is recommended to upgrade to Pomerium version 0.15.6 or later. Additionally, clearing the databroker service by clearing Redis or restarting the in-memory databroker can ensure that the claims are updated and policy evaluation is accurate.
There is no specific workaround mentioned for this vulnerability. However, regularly updating Pomerium to the latest version and ensuring proper configuration of the allowed_idp_claims feature can help mitigate the impact of this vulnerability.
References
Related vulnerabilities
Recent vulnerabilities recorded for github.com/pomerium/pomerium.
