{"id":"CVE-2026-91984","kind":"vulnerability","aliases":["CVE-2026-91984","GHSA-w39f-h553-h2mx","GO-2026-6755"],"related":[],"title":"Vikunja: Cross-tenant task-position rows can be injected into arbitrary project views via the unvalidated project_view_id in the task position endpoint (v1 and v2) in code.vikunja.io/api","description":"Vikunja: Cross-tenant task-position rows can be injected into arbitrary project views via the unvalidated project_view_id in the task position endpoint (v1 and v2) in code.vikunja.io/api.\n\nNOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.\n\n(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)\n\nThe additional affected modules and versions are: code.vikunja.io/api before v2.6.0.","summary":"The task position endpoint in code.vikunja.io/api (v1 and v2) accepts a project_view_id without checking that it belongs to the caller's tenant. An attacker can insert task position rows into project views they do not own.","severity":"medium","cvss":5.3,"epss":0.00264,"exploited":false,"exploited_at":null,"products":[{"name":"code.vikunja.io/api","fixed":[],"affected":"all versions","ecosystem":"go"}],"ecosystems":["go"],"tags":["go","package","self-hosted","vikunja"],"not_affected_if":["already-on-v2.6.0"],"how_to_check":"Check the version of code.vikunja.io/api in go.mod, or the running Vikunja build; affected versions are those before v2.6.0.","fix":"Upgrade code.vikunja.io/api to v2.6.0 or later.","status":"open","published_at":"2026-09-15T16:17:55+00:00","first_seen_at":"2026-10-23T19:13:08+00:00","triaged_at":"2026-10-23T21:48:57+00:00","updated_at":"2026-10-23T21:48:57+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-23T21:48:57Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade code.vikunja.io/api to v2.6.0 or later.","reach":"internet","impact":"medium","summary":"The task position endpoint in code.vikunja.io/api (v1 and v2) accepts a project_view_id without checking that it belongs to the caller's tenant. An attacker can insert task position rows into project views they do not own.","category":"package","who_cares":["vikunja","self-hosted","go"],"confidence":0.7,"needs_auth":"yes","worst_case":"Authenticated user writes task position rows into other tenants' project views.","analyst_note":"","how_to_check":"Check the version of code.vikunja.io/api in go.mod, or the running Vikunja build; affected versions are those before v2.6.0.","needs_analyst":false,"not_affected_if":["already-on-v2.6.0"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000755,"input_tokens":3013,"output_tokens":908,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':35A,43A,46A '-6755':44A '-91984':36A,47A '/api':33A,50A,64B,174C '/api.':125C 'accept':68B 'addit':134C,166C 'advisori':129C 'affect':167C 'arbitrari':13A,105C 'attack':84B 'automat':140C 'belong':77B 'caller':80B 'caus':150C 'check':74B 'code.vikunja.io':32A,49A,63B,124C,173C 'code.vikunja.io/api':31A,48A,62B,172C 'code.vikunja.io/api.':123C 'contain':133C 'could':137C 'cross':3A,95C 'cross-ten':2A,94C 'cve':34A,45A 'edit':161C 'endpoint':26A,60B,118C 'fals':152C 'false-posit':151C 'ghsa':38A 'ghsa-w39f-h553-h2mx':37A 'go':42A,51B,144C 'h2mx':41A 'h553':40A 'host':55B 'id':21A,72B,113C 'inject':11A,103C 'insert':86B 'map':141C 'modul':145C,168C 'note':126C 'packag':52B 'pleas':158C 'posit':7A,25A,59B,88B,99C,117C,153C 'project':14A,19A,70B,91B,106C,111C 'report':132C,154C,164C 'row':8A,89B,100C 'scanner':157C 'self':54B 'self-host':53B 'sourc':128C 'standard':143C 'suggest':159C 'task':6A,24A,58B,87B,98C,116C 'task-posit':5A,97C 'tenant':4A,82B,96C 'unvalid':18A,110C 'v1':27A,65B,119C 'v2':29A,67B,121C 'v2.6.0':176C 'version':135C,146C,170C 'via':16A,108C 'view':15A,20A,71B,92B,107C,112C 'vikunja':1A,56B,93C 'vulner':156C 'w39f':39A 'without':73B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-09-15T16:17:55+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"govuln","external_id":"GO-2026-6755","url":"https://pkg.go.dev/vuln/GO-2026-6755","severity":null,"published_at":"2026-10-19T21:08:26+00:00","modified_at":"2026-10-19T21:08:26+00:00","first_seen_at":"2026-10-23T19:13:08+00:00","fetched_at":"2026-10-23T19:13:08+00:00","note":null},{"source":"epss","external_id":"CVE-2026-91984","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-91984","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:43+00:00","fetched_at":"2026-10-23T19:13:43+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-91984","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91984","severity":null,"published_at":"2026-09-15T16:17:55+00:00","modified_at":"2026-09-17T20:18:54+00:00","first_seen_at":"2026-10-23T19:35:23+00:00","fetched_at":"2026-10-23T19:35:23+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}