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Coder's OIDC authentication allows email with partially matching domain to register

High severity GitHub Reviewed Published Mar 4, 2024 in coder/coder • Updated Mar 21, 2024

Package

gomod github.com/coder/coder (Go)

Affected versions

<= 0.27.3

Patched versions

None
gomod github.com/coder/coder/v2 (Go)
>= 2.8.0, < 2.8.4
>= 2.7.0, < 2.7.3
< 2.6.1
2.8.4
2.7.3
2.6.1

Description

Summary

A vulnerability in Coder's OIDC authentication could allow an attacker to bypass the CODER_OIDC_EMAIL_DOMAIN verification and create an account with an email not in the allowlist. Deployments are only affected if the OIDC provider allows users to create accounts on the provider (such as public providers like google.com).

Details

During OIDC registration, the user's email was improperly validated against the allowed CODER_OIDC_EMAIL_DOMAINs. This could allow a user with a domain that only partially matched an allowed domain to successfully login or register (e.g. [email protected] would match the allowed domain corp.com).

An attacker could register a domain name that exploited this vulnerability and register on a Coder instance with a public OIDC provider.

Impact

Coder instances with OIDC enabled and protected by the CODER_OIDC_EMAIL_DOMAIN configuration.

Coder instances using a private OIDC provider are not affected, as arbitrary users cannot register through a private OIDC provider without first having an account on the provider.

Public OIDC providers (such as google.com without permitted domains set on the OAuth2 App) are impacted.

GitHub authentication and external authentication are not impacted.

Was my deployment impacted?

To check if your deployment was exploited:

  • View the audit log on your deployment for unexpected registered users (using the action:register filter)
  • Check the users list for unexpected users
    • Users created via this exploit will have a domain that ends with one of the allowed domains but doesn’t fully match (e.g. @exploitcorp.com instead of @corp.com)

Patched Versions

This vulnerability is remedied in

  • v2.8.4
  • v2.7.3
  • v2.6.1

All versions prior to these patches are affected by the vulnerability. It is recommended that customers upgrade their deployments as soon as possible if they are utilizing OIDC authentication with the CODER_OIDC_EMAIL_DOMAIN setting.

Thanks

References

GHSA-7cc2-r658-7xpf
coder/coder@4439a92
https://nvd.nist.gov/vuln/detail/CVE-2024-27918

References

@kylecarbs kylecarbs published to coder/coder Mar 4, 2024
Published to the GitHub Advisory Database Mar 4, 2024
Reviewed Mar 4, 2024
Published by the National Vulnerability Database Mar 21, 2024
Last updated Mar 21, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

EPSS score

0.045%
(17th percentile)

Weaknesses

CVE ID

CVE-2024-27918

GHSA ID

GHSA-7cc2-r658-7xpf

Source code

Credits

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