Medium severity · published Oct 27, 2026
CVE-2026-117554
Admidio before 5.0.17 Event Guest Restriction Bypass via events_function.php
New
4.3
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AD
admidio · admidio
before 5.0.17 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-117554
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-117554
github.com
https://github.com/Admidio/admidio
github.com
https://github.com/Admidio/admidio/blob/v5.0.16/modules/events/events_function.php#L446-L462
github.com
https://github.com/Admidio/admidio/commit/5b0ee3585d2a69a6e85fee00b7b93f3ebc1e44d9
github.com
https://github.com/Admidio/admidio/issues/2231
github.com
https://github.com/Admidio/admidio/releases/tag/v5.0.17
github.com
https://github.com/Admidio/admidio/security/advisories/GHSA-92g9-59rr-c3qg
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Admidio is a free, open source user management system for websites of organizations and groups