{"id":"CVE-2026-117554","kind":"vulnerability","aliases":["CVE-2026-117554"],"related":[],"title":"Admidio: members can fill event seats by submitting guest field","description":"Admidio before 5.0.17 contains an improper access control vulnerability that allows authenticated members to register event guests by submitting the additional_guests field when guests are disallowed. Attackers can set additional_guests to the remaining seat count in modules/events/events_function.php to exhaust event capacity and block other members from registering.","summary":"Admidio before 5.0.17 lets an authenticated member register event guests even when guests are disallowed, by sending the additional_guests field. An attacker can set that field to the remaining seat count and block other members from registering for the event.","severity":"medium","cvss":5.3,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["admidio","package","php","self-hosted"],"not_affected_if":["admidio-5.0.17-or-later","events-module-unused"],"how_to_check":"- Check the installed Admidio version (`5.0.17` or later is fixed).\n- Look for the guest handling in `modules/events/events_function.php` in the installed code.","fix":"- Upgrade Admidio to `5.0.17` or later.","status":"open","published_at":"2026-10-27T14:16:35+00:00","first_seen_at":"2026-10-27T14:32:18+00:00","triaged_at":"2026-10-27T14:33:12+00:00","updated_at":"2026-10-27T14:33:12+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-27T14:33:12Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Admidio to `5.0.17` or later.","reach":"internet","title":"Admidio: members can fill event seats by submitting guest field","impact":"low","summary":"Admidio before 5.0.17 lets an authenticated member register event guests even when guests are disallowed, by sending the additional_guests field. An attacker can set that field to the remaining seat count and block other members from registering for the event.","category":"package","nicknames":[],"who_cares":["admidio","self-hosted","php"],"confidence":0.7,"needs_auth":"yes","worst_case":"Member blocks other members from registering for events by filling seats","analyst_note":"","how_to_check":"- Check the installed Admidio version (`5.0.17` or later is fixed).\n- Look for the guest handling in `modules/events/events_function.php` in the installed code.","needs_analyst":false,"not_affected_if":["admidio-5.0.17-or-later","events-module-unused"],"who_is_affected":"Sites running Admidio older than `5.0.17` that use the events module with registration where guests are disallowed. Any member with a normal login can exploit it. Sites without the events module, or with no logged-in members able to register, can skip it.","user_interaction":"no","needs_special_setup":"no","severity_if_unknown":"medium"},"cost_usd":0.000555,"input_tokens":3318,"output_tokens":447,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-117554':13A,16A '-2026':12A,15A '5.0.17':25B,66C 'access':70C 'addit':41B,84C,94C 'admidio':1A,17B,23B,64C 'allow':74C 'attack':45B,91C 'authent':28B,75C 'block':56B,108C 'capac':106C 'contain':67C 'control':71C 'count':54B,100C 'cve':11A,14A 'disallow':37B,90C 'even':33B 'event':5A,31B,63B,79C,105C 'exhaust':104C 'field':10A,43B,49B,86C 'fill':4A 'guest':9A,32B,35B,42B,80C,85C,88C,95C 'host':22B 'improp':69C 'let':26B 'member':2A,29B,58B,76C,110C 'modules/events/events_function.php':102C 'packag':18B 'php':19B 'regist':30B,60B,78C,112C 'remain':52B,98C 'seat':6A,53B,99C 'self':21B 'self-host':20B 'send':39B 'set':47B,93C 'submit':8A,82C 'vulner':72C","nicknames":[],"mitigations":[],"who_affected":"Sites running Admidio older than `5.0.17` that use the events module with registration where guests are disallowed. Any member with a normal login can exploit it. Sites without the events module, or with no logged-in members able to register, can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:35+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":"nvd","external_id":"CVE-2026-117554","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117554","severity":null,"published_at":"2026-10-27T14:16:35+00:00","modified_at":"2026-10-27T14:16:36+00:00","first_seen_at":"2026-10-27T14:32:18+00:00","fetched_at":"2026-10-27T14:32:18+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"}