Co-booker token disclosure via unchecked group key
Published Oct 1, 2026 · Updated Oct 1, 2026
Insecure direct object reference in NSquared Simply Schedule Appointments 1.6.12.31 and earlier lets remote authenticated users read co-booker data. The appointment REST controller accepts complete_group without validating the user-controlled group key, returning other appointments' names, email addresses, and id_token values as public_token. Subscriber access and a valid id_token for one appointment in the group are required; exposed tokens also authorize reading or overwriting those appointments' metadata or canceling them.
Summary
What happened
Insecure direct object reference in NSquared Simply Schedule Appointments 1.6.12.31 and earlier lets remote authenticated users read co-booker data. The appointment REST controller accepts complete_group without validating the user-controlled group key, returning other appointments' names, email addresses, and id_token values as public_token. Subscriber access and a valid id_token for one appointment in the group are required; exposed tokens also authorize reading or overwriting those appointments' metadata or canceling them.
The record
- CVE
- CVE-2026-91109
- Published
- Oct 1, 2026
- Updated
- Oct 1, 2026
- Vendor
- NSquared
- Product
- Simply Schedule Appointments
- Classifications
- CWE-639, T1213
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 1, 2026CVE publishedPublication date reported by the CVE source.
- Oct 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <=1.6.12.31
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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