Simply Schedule Appointments <= 1.6.12.31 - Insecure Direct Object Reference to Authenticated (Subscriber+) Sensitive Information Disclosure via 'complete_group' Parameter

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-91109
StatePUBLISHED
AssignerWordfence
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-01 04:18:21 UTC
Updated2026-10-03 16:16:41 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS: 0.003210000 probability, percentile 0.228830000 (date 2026-10-05)

Problem Types: CWE-639 | CWE-639 CWE-639 Authorization Bypass Through User-Controlled Key

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Croixhaug Simply Schedule Appointments affected 1.6.12.31 semver Not specified

References

ReferenceSourceLinkTags
plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/... [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/... [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/... [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/simply-schedule-appointments/tags/1.6.12.27/includes/... [email protected] plugins.trac.wordpress.org
www.wordfence.com/threat-intel/vulnerabilities/id/d1cd3de2-16ca-4f95-ad6f-47cfb... [email protected] www.wordfence.com
plugins.trac.wordpress.org/changeset/3709365/simply-schedule-appointments/trunk/includes... [email protected] plugins.trac.wordpress.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: jtb75 (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-09-14T19:51:27.000ZVendor Notified
CNA2026-09-30T15:10:42.000ZDisclosed

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