{"id":"CVE-2026-123511","kind":"vulnerability","aliases":["CVE-2026-123511"],"related":[],"title":"Vikunja: CalDAV requests can flood the database with dummy tasks","description":"Vikunja before 2.7.1 contains an uncontrolled resource consumption vulnerability that allows authenticated CalDAV clients to create unbounded dummy tasks by sending VTODOs with thousands of RELATED-TO properties. Attackers can repeat unknown related UIDs in a single PUT request to generate thousands of task, relation, and event rows, bloating the database and overloading the event pipeline.","summary":"Vikunja before 2.7.1 lets a logged-in CalDAV client send a single calendar to-do item with thousands of RELATED-TO properties, and each unknown related ID creates a task. An attacker can bloat the database and overload the event pipeline, which can slow or disrupt the service.","severity":"medium","cvss":5.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["caldav","package","self-hosted","vikunja"],"not_affected_if":["auth-required","managed-hosting","no-caldav"],"how_to_check":null,"fix":"- Vikunja: move to `2.7.1` or later.","status":"open","published_at":"2026-11-08T02:16:39+00:00","first_seen_at":"2026-11-08T02:21:08+00:00","triaged_at":"2026-11-08T02:25:23+00:00","updated_at":"2026-11-08T02:25:23+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-08T02:25:23Z","model":"claude-haiku-5-5","output":{"fix":"- Vikunja: move to `2.7.1` or later.","reach":"network","title":"Vikunja: CalDAV requests can flood the database with dummy tasks","impact":"low","summary":"Vikunja before 2.7.1 lets a logged-in CalDAV client send a single calendar to-do item with thousands of RELATED-TO properties, and each unknown related ID creates a task. An attacker can bloat the database and overload the event pipeline, which can slow or disrupt the service.","audience":"businesses","category":"package","nicknames":[],"who_cares":["vikunja","self-hosted","caldav"],"confidence":0.7,"fix_status":"available","needs_auth":"yes","worst_case":"Database and event pipeline are flooded, degrading service availability","analyst_note":"","how_to_check":"- Check the installed Vikunja version; `2.7.0` or earlier is affected.\n- Confirm whether CalDAV access is enabled for your Vikunja instance.\n- unknown for other checks; the sources do not say.","plain_action":"","needs_analyst":false,"not_affected_if":["no-caldav","managed-hosting","auth-required"],"who_is_affected":"Self-hosted or managed Vikunja instances where users can connect CalDAV clients. An attacker needs a valid account, so instances with open registration or many accounts face more risk. Instances without CalDAV use or with only trusted users are less exposed.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000694,"input_tokens":4309,"output_tokens":527,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-123511':13A,16A '-2026':12A,15A '2.7.1':25B,76C 'allow':84C 'attack':57B,103C 'authent':85C 'bloat':59B,123C 'caldav':2A,17B,31B,86C 'calendar':36B 'client':32B,87C 'consumpt':81C 'contain':77C 'creat':53B,89C 'cve':11A,14A 'databas':7A,61B,125C 'disrupt':71B 'dummi':9A,91C 'event':65B,121C,129C 'flood':5A 'generat':115C 'host':21B 'id':52B 'item':40B 'let':26B 'log':29B 'logged-in':28B 'overload':63B,127C 'packag':18B 'pipelin':66B,130C 'properti':47B,102C 'put':112C 'relat':45B,51B,100C,107C,119C 'related-to':44B,99C 'repeat':105C 'request':3A,113C 'resourc':80C 'row':122C 'self':20B 'self-host':19B 'send':33B,94C 'servic':73B 'singl':35B,111C 'slow':69B 'task':10A,55B,92C,118C 'thousand':42B,97C,116C 'to-do':37B 'uid':108C 'unbound':90C 'uncontrol':79C 'unknown':50B,106C 'vikunja':1A,22B,23B,74C 'vtodo':95C 'vulner':82C","nicknames":[],"mitigations":[],"who_affected":"Self-hosted or managed Vikunja instances where users can connect CalDAV clients. An attacker needs a valid account, so instances with open registration or many accounts face more risk. Instances without CalDAV use or with only trusted users are less exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["caldav","medium","package","selfhosted","vikunja"],"campaign_type":null,"search_a":"'-123511':13A,16A '-2026':12A,15A 'caldav':2A 'cve':11A,14A 'databas':7A 'dummi':9A 'flood':5A 'request':3A 'task':10A 'vikunja':1A","search_b":"'2.7.1':25B 'attack':57B 'bloat':59B 'caldav':17B,31B 'calendar':36B 'client':32B 'creat':53B 'databas':61B 'disrupt':71B 'event':65B 'host':21B 'id':52B 'item':40B 'let':26B 'log':29B 'logged-in':28B 'overload':63B 'packag':18B 'pipelin':66B 'properti':47B 'relat':45B,51B 'related-to':44B 'self':20B 'self-host':19B 'send':33B 'servic':73B 'singl':35B 'slow':69B 'task':55B 'thousand':42B 'to-do':37B 'unknown':50B 'vikunja':22B,23B","search_c":"'2.7.1':76C 'allow':84C 'attack':103C 'authent':85C 'bloat':123C 'caldav':86C 'client':87C 'consumpt':81C 'contain':77C 'creat':89C 'databas':125C 'dummi':91C 'event':121C,129C 'generat':115C 'overload':127C 'pipelin':130C 'properti':102C 'put':112C 'relat':100C,107C,119C 'related-to':99C 'repeat':105C 'request':113C 'resourc':80C 'row':122C 'send':94C 'singl':111C 'task':92C,118C 'thousand':97C,116C 'uid':108C 'unbound':90C 'uncontrol':79C 'unknown':106C 'vikunja':74C 'vtodo':95C 'vulner':82C","first_public_at":"2026-10-22T10:03:57+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/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":"nvd","external_id":"CVE-2026-123511","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123511","severity":null,"published_at":"2026-11-08T02:16:39+00:00","modified_at":"2026-11-08T02:16:39+00:00","first_seen_at":"2026-11-08T02:21:08+00:00","fetched_at":"2026-11-08T02:21:08+00:00","note":null}],"documents":[{"id":99171,"url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-c934-xjq2-mrg3","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-10-22T10:03:57+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"},{"id":99172,"url":"https://www.vulncheck.com/advisories/vikunja-before-2.7.1-resource-exhaustion-via-caldav-vtodo-related-to-entries","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}