id: GO-TEST-ID
modules:
    - module: github.com/concourse/concourse
      versions:
        - introduced: 6.3.0
          fixed: 6.3.1
        - introduced: 6.4.0
          fixed: 6.4.1
    - module: github.com/concourse/dex
      versions:
        - introduced: 6.3.0
          fixed: 6.3.1
        - introduced: 6.4.0
          fixed: 6.4.1
summary: |-
    GitLab auth uses full name instead of username as user ID, allowing
    impersonation in github.com/concourse/concourse
description: |-
    ### Impact

    Installations which use the GitLab auth connector are vulnerable to identity
    spoofing by way of configuring a GitLab account with the same full name as
    another GitLab user who is granted access to a Concourse team by having their
    full name listed under `users` in the team configuration or given to the
    `--gitlab-user` flag.

    See the [GitLab auth docs](https://concourse-ci.org/gitlab-auth.html) for
    details.

    Concourse installations which do not configure the GitLab auth connector are not
    affected.

    ### Patches

    Concourse [v6.3.1](https://github.com/concourse/concourse/releases/tag/v6.3.1)
    and [v6.4.1](https://github.com/concourse/concourse/releases/tag/v6.4.1) were
    both released with a fix on August 4th, 2020.

    Both versions change the GitLab connector to use the username, rather than the
    full name. This was always the intent, and the previous behavior was originally
    reported as a bug (concourse/dex#7) prior to being reported as a security issue.

    Any Concourse teams which configure GitLab users will have to switch each user
    from their full name to their username upon upgrading to these versions.

    ### Workarounds

    GitLab groups do not have this vulnerability, so GitLab users may be moved into
    groups which are then configured in the Concourse team.

    ### References

    * concourse/dex#12: PR with the fix

    ### For more information

    If you have any questions or comments about this advisory, you may reach us
    privately at
    [concourseteam+security@gmail.com](mailto:concourseteam+security@gmail.com).
cves:
    - CVE-2020-5415
ghsas:
    - GHSA-627p-rr78-99rj
references:
    - advisory: https://github.com/concourse/concourse/security/advisories/GHSA-627p-rr78-99rj
    - web: https://tanzu.vmware.com/security/cve-2020-5415
notes:
    - lint: 'description: possible markdown formatting (found ### )'
    - lint: 'description: possible markdown formatting (found [GitLab auth docs](https://concourse-ci.org/gitlab-auth.html))'
    - lint: 'description: possible markdown formatting (found `users`)'
    - lint: 'modules[0] "github.com/concourse/concourse": 4 versions do not exist: 6.3.0, 6.3.1, 6.4.0, 6.4.1'
    - lint: 'modules[1] "github.com/concourse/dex": 4 versions do not exist: 6.3.0, 6.3.1, 6.4.0, 6.4.1'
    - lint: 'summary: too long (found 115 characters, want <=100)'
source:
    id: GHSA-627p-rr78-99rj