{"id":"CVE-2026-56765","summary":"Vikunja - Unauthenticated Instance-Wide Data Breach via Link Share Hash Disclosure Chained with Cross-Project Attachment IDOR","details":"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.","aliases":["GHSA-2pv8-4c52-mf8j","GO-2026-4855"],"modified":"2026-07-15T01:48:55.283616609Z","published":"2026-07-10T13:57:59.648Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56765.json","cna_assigner":"VulnCheck","cwe_ids":["CWE-639"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/56xxx/CVE-2026-56765.json"},{"type":"ADVISORY","url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-2pv8-4c52-mf8j"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56765"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/vikunja-unauthenticated-instance-wide-data-breach-via-link-share-hash-disclosure-chained-with-cross-project-attachment-idor"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/go-vikunja/vikunja","events":[{"introduced":"0"},{"fixed":"6d5d3e051f4f9f6d72f5d1d552c2d90910fccb28"}],"database_specific":{"source":["AFFECTED_FIELD","DESCRIPTION"],"extracted_events":[{"introduced":"0"},{"fixed":"2.2.1"}]}}],"versions":["v2.2.0","v2.1.0","v2.0.0","v1.1.0","v1.0.0","v1.0.0-rc4","v1.0.0-rc3","v1.0.0-rc2","v1.0.0-rc1","v1.0.0-rc0","v0.24.1","v0.23.0","v0.22.1","v0.22.0","v0.21.0","v0.20.4","v0.20.3","v0.20.1","v0.20.0","v0.19.2","v0.19.1","v0.19.0","v0.18.1","v0.18.0","v0.17.0","v0.16.0","v0.15.0","v0.14.0","v0.13","v0.12","v0.11","v0.10","v0.9","v0.8","v0.7","v0.6","v0.5","v0.4","v0.3","v0.2","v0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-56765.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"}]}