Modern Events Calendar Lite Cross-site Scripting

Cross-site scripting vulnerability in Modern Events Calendar Lite versions prior to 6.3.0 allows remote an authenticated attacker to inject an arbitrary script via unspecified vectors. (2022-06-16, CVE-2022-30533)

Authenticated (admin+ user) Stored Cross-Site Scripting (XSS) in Modern Events Calendar Lite (WordPress plugin) <= 6.5.1 (2022-04-14, CVE-2022-27848)

The Modern Events Calendar Lite WordPress plugin before 6.4.0 does not sanitize and escape some of the Hourly Schedule parameters which could allow users with a role as low as contributor to perform Stored Cross-Site Scripting attacks (2022-03-21, CVE-2022-0364)

The Modern Events Calendar Lite WordPress plugin before 6.2.0 alloed any logged-in user, even a subscriber user, may add a category whose parameters are incorrectly escaped in the admin panel, leading to stored XSS. (2022-01-17, CVE-2021-25046)

The Modern Events Calendar Lite WordPress plugin before 6.1.5 does not sanitise and escape the current_month_divider parameter of its mec_list_load_more AJAX call (available to both unauthenticated and authenticated users) before outputting it back in the response, leading to a Reflected Cross-Site Scripting issue (2021-12-13, CVE-2021-24925)

The Modern Events Calendar Lite WordPress plugin before 5.22.3 does not properly sanitize or escape values set by users with access to adjust settings withing wp-admin. (2021-11-01, CVE-2021-24716)

The Modern Events Calendar Lite WordPress plugin before 5.22.2 does not escape some of its settings before outputting them in attributes, allowing high privilege users to perform Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed. (2021-10-04, CVE-2021-24687)

Unvalidated input and lack of output encoding in the Modern Events Calendar Lite WordPress plugin, versions before 5.16.5, did not sanitise the mic_comment field (Notes on time) when adding/editing an event, allowing users with privilege as low as author to add events with a Cross-Site Scripting payload in them, which will be triggered in the frontend when viewing the event. (2021-03-18, CVE-2021-24147)

Multiple Stored Cross-site scripting (XSS) vulnerabilities in the Webnus Modern Events Calendar Lite plugin through 5.1.6 for WordPress allows remote authenticated users (with minimal permissions) to inject arbitrary JavaScript, HTML, or CSS via Ajax actions. This affects mec_save_notifications and import_settings. (2020-02-28, CVE-2020-9459)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>