CVE-2026-123503

A vulnerability in Vikunja before version 2.2.1 allows unauthorized access to share hashes and downloading/deleting all file attachments across the instance. An authorization flaw in the LinkSharing.ReadAll and GetTaskAttachment endpoints enables privilege escalation to admin-level shares.

Vikunja from 1.0.0 before 2.7.1 contains an uncontrolled resource consumption vulnerability that allows authenticated users to bypass service.maxitemsperpage by sending page=0 to /api/v1 list endpoints. Attackers can self-register and repeatedly request page=0 to force unbounded SQL queries, memory materialisation, and per-row query fan-out, degrading availability for other users.

Vikunja before 2.7.1 contains a missing authentication vulnerability that allows attackers holding a stolen session to enroll and enable TOTP without the account password. Attackers can call the TOTP enroll and enable endpoints with their own secret to lock the owner out, persisting even after password reset.

Vikunja before 2.7.1 contains a stored CSS injection vulnerability that allows authenticated users with project write access to inject arbitrary CSS via unsanitized table-cell data-background-color attributes. Attackers can store crafted task descriptions or comments to render full-viewport phishing overlays or force zero-click outbound background-image requests that deanonymize viewers.

Vikunja before 2.7.1 contains an insufficient session expiration vulnerability that allows holders of revoked access tokens to keep authenticating because SetupTokenMiddleware skips session and account-status checks. Attackers with a stolen token can, after logout, password reset, or account disabling, mint OAuth sessions via /oauth/authorize or tk_ API tokens for persistent access.

Vikunja from 2.4.0 before 2.7.1 contains an authorization bypass vulnerability that allows token holders to perform unintended operations due to colliding v1 and v2 API token permission keys. Attackers with a token scoped to read project backgrounds can delete them via the v2 DELETE background route, and bucket create-only tokens can update existing buckets.

Vikunja before 2.7.1 contains a mass assignment vulnerability that allows any authenticated user to set the read-only external_id field through the team create and update endpoints. Attackers can tag a team they create or administer as externally managed, permanently blocking removal of every member and causing SSO members to be dropped from the team at their next login.

Vikunja before 2.7.1 allocates memory without limits in its Trello, Todoist and Microsoft To Do migration importers, which buffer remote attachment downloads and API responses in memory without size caps. Authenticated users can start a migration that references huge attacker-served attachments or yields oversized API responses, exhausting memory and crashing the shared API process for all tenants.

Vikunja from 0.23.0 before 2.7.1 contains an information disclosure vulnerability that allows project collaborators with write access to read tasks from inaccessible projects by registering webhooks. Because webhook payloads are built with the triggering user's permissions, attackers receive related_tasks titles, descriptions and metadata from private projects whenever another user modifies a linked task.

Vikunja before 2.7.1 contains an uncontrolled resource consumption vulnerability that allows authenticated users to exhaust server memory by requesting avatars at many distinct sizes. Attackers can upload a noisy avatar and fetch it at each size up to 1024, caching roughly a gigabyte per account without eviction and causing the API process to be OOM-killed.