Vulnerability · Published Oct 1, 2026 · Assigned by Wordfence

CVE-2026-91109Simply Schedule Appointments <= 1.6.12.31 - Insecure Direct Object Reference to Authenticated (Subscriber+) Sensitive Information Disclosure via 'complete_group' Parameter

Medium 6.5

In plain English

A medium-severity authorization bypass via user-controlled key in Simply Schedule Appointments from croixhaug. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.3%top 75.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
croixhaug	Simply Schedule Appointments	0 – through 1.6.12.31

Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

In plain English

Official description

Affected products (as reported)

References