CVE-2026-104000 Cross-site scripting in Simply Schedule Appointments
Unauthenticated attackers can inject scripts via the status parameter, leading to admin session hijacking due to default debug logging exposure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-104000?
CVE-2026-104000 is a high-severity cross-site scripting vulnerability in croixhaug Simply Schedule Appointments, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The Simply Schedule Appointments plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'status' parameter in all versions up to, and including, 1.6.12.35 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The malicious payload is stored unconditionally because debug logging is enabled by default, and the debug-log viewer is accessible to anyone holding the site-wide Support PIN (an HMAC-MD5 of AUTH_SALT displayed in wp-admin), meaning the injected script will execute against the administrator's session during ordinary support or troubleshooting workflows.
Weakness: CWE-79
Which versions are affected by CVE-2026-104000?
How do I fix CVE-2026-104000?
No fix has been published for CVE-2026-104000 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-104000 being exploited?
There is no known exploitation of CVE-2026-104000 in the wild and no public exploit code.
Sources
Also known as GHSA-hh9h-qh43-jq4f.