{"id":"CVE-2026-56765","published":"2026-07-10T13:57:59Z","modified":"2026-07-10T17:00:55Z","title":"Vikunja - Unauthenticated Instance-Wide Data Breach via Link Share Hash Disclosure Chained with Cross-Project…","vendor":"Vikunja","product":"Vikunja","tier":"tail","description":{"text":"Vikunja before 2.2.1 contains an authorization flaw where the LinkSharing.ReadAll endpoint exposes share hashes to users with read access, enabling permission escalation to admin-level shares. The GetTaskAttachment endpoint performs permission checks against user-supplied task IDs but fetches attachments by sequential ID without verifying ownership, allowing attackers to download and delete all file attachments across all projects instance-wide.","provenance":"source","from":"CVE.org"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.00512,"percentile":0.43507,"provenance":"source"},"cwes":[{"id":"CWE-639","name":"Authorization Bypass Through User-Controlled Key"}],"references":[{"url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j","tags":["vendor-advisory"]},{"url":"https://www.vulncheck.com/advisories/vikunja-unauthenticated-instance-wide-data-breach-via-link-share-hash-disclosure-chained-with-cross-project-attachment-idor","tags":["third-party-advisory"]}],"priority":{"score":15.6,"factors":[{"name":"EPSS percentile","points":8.7},{"name":"CVSS severity","points":6.86}]},"vendorSlug":"vikunja","affectedVersions":[{"vendor":"Vikunja","product":"Vikunja","versions":["< 2.2.1"]}],"affected":[{"ecosystem":"Go","package":"code.vikunja.io/api","vulnerableRanges":["all versions"],"patched":[],"from":["GO-2026-4855"],"provenance":"source"}],"euvd":{"id":"EUVD-2026-42890","exploited":false,"provenance":"source"},"lineage":{"familyId":"fam-go-vikunja-vikunja-cve-2026-33678","parents":[{"from":"CVE-2026-33678","to":"CVE-2026-56765","relation":"related","confidence":"high","kind":"lineage","evidence":[{"kind":"osv-related","provenance":"source","id":"GHSA-2pv8-4c52-mf8j","via":"reference","url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-jfmm-mjcp-8wq2"},{"kind":"osv-related","provenance":"source","id":"GO-2026-4855","via":"reference","url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-jfmm-mjcp-8wq2"}]},{"from":"CVE-2026-33680","to":"CVE-2026-56765","relation":"related","confidence":"high","kind":"lineage","evidence":[{"kind":"osv-related","provenance":"source","id":"GHSA-2pv8-4c52-mf8j","via":"reference","url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-8hp8-9fhr-pfm9"},{"kind":"osv-related","provenance":"source","id":"GO-2026-4855","via":"reference","url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-8hp8-9fhr-pfm9"}]}]}}