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 deviseinvitable gem always accepts the pending invitation if the user has been invited as shown in this piece of code within the deviseinvitable gem: https://github.com/scambra/deviseinvitable/blob/41f58970ff76fb64382a9b9ea1bd530f7c3adab2/lib/deviseinvitable/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 invitefor expiry period as explained in the gem's documentation: https://github.com/scambra/deviseinvitable#model-configuration-

invitefor: The period the generated invitation token is valid. After this period, the invited resource won’t be able to accept the invitation. When invitefor 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 deviseinvitable gem and should be fixed there and the dependency should be upgraded in Decidim once the fix becomes available.

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

$ bundle update deviseinvitable

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

Decidim::User.invitationnotaccepted.updateall(invitationtoken: nil)

References OWASP ASVS V4.0.3-2.3.1

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