My Calendar <= 2.5.16 - Authenticated Stored Cross-Site Scripting

2018-04-04 00:00
Luigi Gubello

Strategic Overview

Status
Patched in 2.5.17
Affected Plugin
My Calendar – Accessible Event Manager
Affected Version
< 2.5.17
CVSS
6.4Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE pending
View all My Calendar – Accessible Event Manager vulnerabilities

At a glance

This record tracks a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the My Calendar WordPress plugin, affecting versions < 2.5.17. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account. The issue is fixed in version 2.5.17; sites on affected versions should update now. Disclosed April 2018, reported by Luigi Gubello.

Vulnerability Overview

The My Calendar plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘event_time_label’ parameter in versions up to, and including, 2.6.16 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

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')

My Calendar < 2.5.17 carries this weakness at event_time_label, and reaching it takes any authenticated account. 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 My Calendar the fix is 2.5.17: builds < 2.5.17 are affected, anything from 2.5.17 onward is not.

Remediation

Update to version 2.5.17, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to My Calendar: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: My Calendar 2.5.17 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.wordfence.com/threat-intel/vulnerabilities/id/a42dce68-0e64-46a6-926e-b676071744b9

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C