Vikunja before 2.7.1 embeds live password-reset, email-confirmation and account-deletion tokens in the URL query string of emailed links, so the full request URI, including the token, is written to Vikunja's HTTP access log and any reverse-proxy logs when a user clicks the link. Attackers with read access to those logs can replay an unredeemed password-reset token to take over the account or an account-deletion token to confirm the deletion.
CWE-532