Authorization bypass in croixhaug Simply Schedule Appointments
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-639.
Summary
The Simply Schedule Appointments plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 1.6.12.31 via the 'complete_group' parameter due to missing validation on a user controlled key. This makes it possible for authenticated attackers, with subscriber-level access and above, to disclose every co-booker's private per-appointment id_token (exposed as public_token) alongside their PII (name and email address), then use each leaked token to read, overwrite arbitrary appointment meta on, or cancel the co-booker's appointment via the same REST controller. Exploitation requires the attacker to possess a valid id_token for any single appointment within the targeted group booking.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-91109
- 2026-10-03 Alias added: GHSA-hm3p-9g7v-6rfw
- 2026-10-03 CISA SSVC decision points changed
References
Other 6
- https://www.wordfence.com/threat-intel/vulnerabilities/id/d1cd3de2-16ca-4f95-ad6f-47cfbe00c959?source=cve
- https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/class-appointment-model.php#L3160
- https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/class-appointment-model.php#L1966
- https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/class-appointment-model.php#L2315
- https://plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/class-db-model.php#L348
- https://plugins.trac.wordpress.org/changeset/3709365/simply-schedule-appointments/trunk/includes/class-appointment-model.php
More croixhaug vulnerabilities
- TI-2026-46678 WordPress Simply Schedule Appointments plugin <= 1.6.12.10 - SQL Injection vulnerability CVSS 3.1CRITICAL 9.3
- TI-2026-28467 WordPress Simply Schedule Appointments plugin <= 1.6.9.27 - SQL Injection vulnerability CVSS 3.1CRITICAL 9.3
- TI-2026-06865 Appointment Booking Calendar <= 1.6.11.8 - Unauthenticated SQL Injection via 'append_where_sql' Parameter CVSS 3.1HIGH 7.5
- TI-2026-62275 Missing authorization in croixhaug Simply Schedule Appointments CVSS 3.1HIGH 7.5
- TI-2026-58265 WordPress Simply Schedule Appointments plugin <= 1.6.12.23 - Cross Site Request Forgery (CSRF) vulnerability CVSS 3.1HIGH 8.8
- TI-2026-30684 WordPress Simply Schedule Appointments plugin < 1.6.11.2 - Sensitive Data Exposure vulnerability CVSS 3.1HIGH 7.5
Sources
- CVE-2026-91109 · CVE Program
- CVE-2026-91109 · NVD
- FIRST EPSS
- GHSA-hm3p-9g7v-6rfw · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences