| 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 |
