QuickCal <= 1.0.20 - Unauthenticated Stored Cross-Site Scripting via Custom Field Parameters
Strategic Overview
- Status
- Unpatched
- Affected Plugin
- QuickCal
- Affected Version
<= 1.0.20- CVSS
- 7.2High
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2026-15984
At a glance
CVE-2026-15984 is a high-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the QuickCal WordPress plugin, affecting versions <= 1.0.20. It carries a CVSS score of 7.2 (reachable over the network; low attack complexity). Exploitation requires no authentication. No fixed release has been reported yet; treat installations running this software as exposed. Disclosed September 2026, reported by adhikara13.
Vulnerability Overview
The QuickCal plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Custom Field Parameters in all versions up to, and including, 1.0.20 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 nonce guarding the unauthenticated booked_add_appt AJAX action is publicly embedded on any page rendering the booking calendar shortcode, making it trivially obtainable by unauthenticated attackers without any prior account or privilege.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Reaching this weakness in QuickCal <= 1.0.20 takes no account at all. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.
Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. No fixed build of this plugin is recorded for QuickCal yet, so installs running <= 1.0.20 stay exposed until the vendor ships one.
Remediation
No known patch available. Please review the vulnerability's details in depth and employ mitigations based on your organization's risk tolerance. It may be best to uninstall the affected software and find a replacement.
How does WordSec protect against this?
Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. No patched version is recorded yet, which is the case where a filtering layer matters most, because there is nothing to update to.
- Firewall
- Login Security
- Alerts
External References
Related records
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