Strategic Overview
- Status
- Patched in 1.2.2
- Affected Plugin
- Availability Calendar
- Affected Version
<= 1.2.1- CVSS
- 5.5Medium
- Weakness type
- CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CVE
CVE-2021-24604
At a glance
CVE-2021-24604 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Availability Calendar WordPress plugin, affecting versions <= 1.2.1. It carries a CVSS score of 5.5 (reachable over the network; low attack complexity). The issue is fixed in version 1.2.2; sites on affected versions should update now. Disclosed August 2021, reported by xiahao.
Vulnerability Overview
The Availability Calendar WordPress plugin before 1.2.2 does not sanitise or escape its Category Names before outputting them in page/post where the associated shortcode is embed, allowing high privilege users to perform Cross-Site Scripting attacks even when the unfiltered_html is disallowed
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 interaction from a victim user.
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Reaching this weakness in Availability Calendar <= 1.2.1 takes a caller who can reach the endpoint. 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. For Availability Calendar the fix is 1.2.2: builds <= 1.2.1 are affected, anything from 1.2.2 onward is not.
Remediation
Update to version 1.2.2, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Availability Calendar: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Availability Calendar 1.2.2 closes this, and updating the plugin is the step that ends it.
- Firewall
- Alerts
External References
Related records
Other vulnerabilities in Availability Calendar
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