What’s Vulnerable › Vulnerabilities

CVE-2026-68581: Vikunja 0.22.0 through 2.3.0 Authentication Bypass via Principal ID Collision

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-02 · updated 2026-10-23
• Weakness: CWE-863

Description

Vikunja versions 0.22.0 through 2.3.0 fail to validate the principal type in API token management. Because user IDs and link-share IDs are independent numeric sequences and both resolve through a generic web.Auth.GetID() interface, a link-share JWT whose numeric ID equals a target user's ID is treated as that user by the /api/v1/tokens endpoints. An authenticated attacker can obtain a target's numeric user ID via authenticated user search, then create link shares on an attacker-writable project until the link-share sequence reaches that value, and use the resulting link-share JWT to list, create, and delete the target user's API tokens (including issuing a new token with attacker-chosen scopes under the target's permissions). Fixed in version 2.4.0.

Affected products

• go-vikunja vikunja: from 0.22.0 before 2.4.0 — fixed in 2.4.0

How to fix

Upgrade to a fixed version: go-vikunja vikunja 2.4.0. Check the vendor advisory for mitigations.

References

• https://github.com/go-vikunja/vikunja/commit/95b7e673fb5ee407498fa4b13e8b4c57847a4a0b
• https://github.com/go-vikunja/vikunja/commit/e6b25bd57b537ef9a72b5acdadf446ca5ef77bfa
• https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vvcv-vpph-h844
• https://www.vulncheck.com/advisories/vikunja-through-authentication-bypass-via-principal-id-collision
• https://github.com/go-vikunja/vikunja/security/advisories/GHSA-vvcv-vpph-h844

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