Is My Calendar safe? Known vulnerabilities and latest version

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 3.8.7. The public `mcs` GET parameter is reflected into post content unsanitized before WordPress core's `do_shortcode` filter runs, allowing an unauthenticated attacker to inject a nested `[my_calendar above=...]` shortcode; `mc_generate_calendar_nav()` then splits the `above` attribute on commas and dispatches each element via `call_user_func()` with no authentication, authorization, or callable allowlist check. This makes it possible for unauthenticated attackers to invoke arbitrary loaded PHP functions, enabling a call chain in which the shortcode `$params` array is passed to `edit_user()` — which PHP coerces to integer `1` as the `$user_id` argument — overwriting the credentials of the initial Administrator account (user ID 1) and granting the attacker full wp-admin access. Exploitation is trivially reachable via the plugin's auto-generated `/my-calendar/` page, which is publicly accessible by default upon plugin activation.

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'before' and 'after' Shortcode Attributes in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'fallback' Shortcode Attribute in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The bypass relies on hex-encoded shortcode attribute payloads (e.g. \x3cscript\x3e), which wp_kses_post cannot strip on save because they appear as literal backslash sequences rather than real HTML tags; WordPress core's shortcode_parse_atts() then calls stripcslashes() at render time, decoding the escapes into real angle brackets before they reach the unescaped sink.

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to time-based blind SQL Injection via the 'mc_auth' parameter in all versions up to, and including, 3.7.8 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 3.7.14 via the 'vcal' parameter due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to enumerate occurrence IDs and access the full iCalendar export of non-public, draft, trashed, and personal calendar events, disclosing sensitive event metadata including titles, descriptions, dates, locations, organizer and host details, permalinks, and related calendar metadata.

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.7.9. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with custom-level access and above, to bypass the moderation and approval workflow by tampering with the POST body to publish events or set other unauthorized statuses such as cancelled or private, in ways their role does not permit. While the UI correctly restricts low-privilege users to a draft-only submit button, this restriction is enforced only client-side, making it trivially bypassable by directly manipulating the POST request.

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `template` attribute of the `[my_calendar_upcoming]` shortcode in all versions up to, and including, 3.7.3. This is due to the use of `stripcslashes()` on user-supplied shortcode attribute values in the `mc_draw_template()` function, which decodes C-style hex escape sequences (e.g., `\x3c` to `<`) at render time, bypassing WordPress's `wp_kses_post()` content sanitization that runs at save time. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Missing Authorization vulnerability in Joe Dolson My Calendar my-calendar allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects My Calendar: from n/a through <= 3.6.16.

The My Calendar WordPress plugin before 3.4.24 does not sanitise and escape some parameters, which could allow users with a role as low as Subscriber to perform Cross-Site Scripting attacks (depending on the permissions set by the admin)

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Joseph C Dolson My Calendar allows Stored XSS.This issue affects My Calendar: from n/a through 3.4.23.

The 'My Calendar' WordPress Plugin, version < 3.4.22 is affected by an unauthenticated SQL injection vulnerability in the 'from' and 'to' parameters in the '/my-calendar/v1/events' rest route.

Cross-Site Request Forgery (CSRF) vulnerability in Joseph C Dolson My Calendar plugin <= 3.4.3 versions.

Cross-Site Request Forgery (CSRF) vulnerability in Joseph C Dolson My Calendar plugin <= 3.3.24.1 versions.

The My Calendar WordPress plugin before 3.2.18 does not sanitise and escape the callback parameter of the mc_post_lookup AJAX action (available to any authenticated user) before outputting it back in the response, leading to a Reflected Cross-Site Scripting issue

The my-calendar plugin before 3.1.10 for WordPress has XSS.