Possibility to circumvent the invitation token expiry period

Impact

The invites feature allows users to accept the invitation for an unlimited amount of time through the password reset functionality.

When using the password reset functionality, the devise_invitable gem always accepts the pending invitation if the user has been invited as shown in this piece of code within the devise_invitable gem: https://github.com/scambra/devise_invitable/blob/41f58970ff76fb64382a9b9ea1bd530f7c3adab2/lib/devise_invitable/models.rb#L198

The only check done here is if the user has been invited but the code does not ensure that the pending invitation is still valid as defined by the invite_for expiry period as explained in the gem's documentation: https://github.com/scambra/devise_invitable#model-configuration-

invite_for: The period the generated invitation token is valid. After this period, the invited resource won’t be able to accept the invitation. When invite_for is 0 (the default), the invitation won’t expire.

Decidim sets this configuration to 2.weeks so this configuration should be respected: https://github.com/decidim/decidim/blob/d2d390578050772d1bdb6d731395f1afc39dcbfc/decidim-core/config/initializers/devise.rb#L134

The bug is in the devise_invitable gem and should be fixed there and the dependency should be upgraded in Decidim once the fix becomes available.

Patches

Update devise_invitable to version 2.0.9 or above by running the following command:

$ bundle update devise_invitable

Workarounds

The invitations can be cancelled directly from the database by running the following command from the Rails console:

> Decidim::User.invitation_not_accepted.update_all(invitation_token: nil)

References

OWASP ASVS V4.0.3-2.3.1

This bug has existed in the devise_invitable gem since this commit which was first included in the v0.4.rc3 release of this gem: https://github.com/scambra/devise_invitable/commit/94d859c7de0829bf63f679ae5dd3cab2b866a098

All versions since then are affected.

This gem was first introduced at its version ~> 1.7.0 to the decidim-admin gem in this commit which was first included in the v0.0.1.alpha3 release of Decidim: https://github.com/decidim/decidim/commit/073e60e2e4224dd81815a784002ebba30f2ebb34

It was first introduced at its version ~> 1.7.0 to the decidim-system gem in this commit which was also first included in the v0.0.1.alpha3 release of Decidim: https://github.com/decidim/decidim/commit/b12800717a689c295a9ea680a38ca9f823d2c454

Credits

This issue was discovered in City of Helsinki's security audit against Decidim 0.27 done during September 2023. The security audit was implemented by Deloitte Finland.