CVE-2026-91109 Information disclosure in Simply Schedule Appointments
Authenticated attackers can leak co-booker PII and tokens to read, modify, or cancel appointments via insecure direct object reference.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-91109?
CVE-2026-91109 is a medium-severity vulnerability in croixhaug Simply Schedule Appointments, published on 1 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
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.
Weakness: CWE-639
Which versions are affected by CVE-2026-91109?
How do I fix CVE-2026-91109?
No fix has been published for CVE-2026-91109 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-91109 being exploited?
There is no known exploitation of CVE-2026-91109 in the wild and no public exploit code.
Sources
Also known as GHSA-hm3p-9g7v-6rfw.