Is WP Compress safe? Known vulnerabilities and latest version

The WP Compress – Instant Performance & Speed Optimization plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 7.22.01. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to link the victim site to an attacker-controlled WP Compress account, overwrite plugin settings to an aggressive live-CDN preset, and gain the shared api_key that authenticates all nopriv HMAC-gated endpoints — enabling full control over cache purging, file deletion, opcode cache invalidation, and other privileged plugin operations. This vulnerability only affects fresh installations or lite/free-mode installs where no api_key is already stored, as the sole guard fails open when the stored key is absent.

The WP Compress – Instant Performance & Speed Optimization plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 7.25.00 The vulnerability exists because the `start_comms` dispatcher (`wps_ic_comms::start_comms`), hooked on every front-end request, gates access only by comparing the caller-supplied `apikey` parameter against the stored plugin API key with no WordPress capability check and no nonce verification, then passes the unvalidated `group`, `setting`, and `value` parameters directly to `change_setting()`, which writes them into the `WPS_IC_SETTINGS` option without an allow-list. This makes it possible for unauthenticated attackers to write arbitrary permission keys into the plugin's settings, causing `wps_ic_users::checkAndAddCaps()` to grant any WordPress role — including Subscriber — the `manage_wpc_settings` capability and thereby achieve plugin-administrator-equivalent control over the plugin's optimization, CDN, and critical-CSS surfaces. The API key required to pass the authorization check can itself be obtained without authentication via the `wpc_send_critical_remote` nopriv AJAX action: when the external critical-CSS service returns an `apiResults` field, `initCritical()` echoes the stored plugin API key back to the caller in a `wp_send_json_success` response, completing the exploit chain entirely without a WordPress login.

Unauthenticated Settings Change in WP Compress <= 7.21.28 versions.

Unauthenticated Remote Code Execution (RCE) in WP Compress < 7.20.01 versions.

The WP Compress – Instant Performance & Speed Optimization plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 7.10.09. This is due to missing or incorrect nonce validation on the (top-level template code) function. This makes it possible for unauthenticated attackers to delete arbitrary WordPress options, including critical ones such as siteurl, home, active_plugins, template, and stylesheet, causing site outage or a full plugin and theme reset via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

The WP Compress WordPress plugin before 7.10.04 does not validate the value of a query parameter that controls the asset CDN host before using it to build the URLs of JavaScript files emitted on the page, leading to Reflected XSS. When a visitor follows a crafted link, the WP Compress WordPress plugin before 7.10.04's loader injects script elements pointing to an attacker-controlled origin, which lets the attacker execute arbitrary JavaScript in the visitor's session on the target site.

Missing Authorization vulnerability in AresIT WP Compress wp-compress-image-optimizer allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects WP Compress: from n/a through <= 6.60.28.

Missing Authorization vulnerability in AresIT WP Compress wp-compress-image-optimizer allows Accessing Functionality Not Properly Constrained by ACLs.This issue affects WP Compress: from n/a through <= 6.50.54.

Weak Authentication vulnerability in AresIT WP Compress wp-compress-image-optimizer allows Authentication Abuse.This issue affects WP Compress: from n/a through <= 6.30.30.

Cross-Site Request Forgery (CSRF) vulnerability in AresIT WP Compress wp-compress-image-optimizer allows Cross Site Request Forgery.This issue affects WP Compress: from n/a through <= 6.30.30.

The WP Compress – Instant Performance & Speed Optimization plugin for WordPress is vulnerable to unauthorized access, modification, and loss of data due to missing capability checks on its on its AJAX functions in all versions up to, and including, 6.30.15. This makes it possible for authenticated attackers, with Subscriber-level access and above, to compromise the site in various ways depending on the specific function exploited - for example, by retrieving sensitive settings and configuration details, or by altering and deleting them, thereby disclosing sensitive information, disrupting the plugin’s functionality, and potentially impacting overall site performance.

The WP Compress – Instant Performance & Speed Optimization plugin for WordPress is vulnerable to Server-Side Request Forgery in all versions up to, and including, 6.30.15 via the init() function. This makes it possible for unauthenticated attackers to make web requests to arbitrary locations originating from the web application and can be used to query information from internal services.

The WP Compress – Instant Performance & Speed Optimization plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the ‘custom_server’ parameter in all versions up to, and including, 6.30.03 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in AresIT WP Compress wp-compress-image-optimizer allows Reflected XSS.This issue affects WP Compress: from n/a through <= 6.20.13.

The WP Compress – Image Optimizer [All-In-One] plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the several functions in versions up to, and including, 6.20.01. This makes it possible for authenticated attackers, with subscriber-level permissions and above, to edit plugin settings, including storing cross-site scripting, in multisite environments.

The WP Compress – Image Optimizer [All-In-One plugin for WordPress is vulnerable to Open Redirect in all versions up to, and including, 6.20.01. This is due to insufficient validation on the redirect url supplied via the 'css' parameter. This makes it possible for unauthenticated attackers to redirect users to potentially malicious sites if they can successfully trick them into performing an action.

Cross-Site Request Forgery (CSRF) vulnerability in WP Compress WP Compress – Image Optimizer [All-In-One].This issue affects WP Compress – Image Optimizer [All-In-One]: from n/a through 6.10.35.

The WP Compress – Image Optimizer plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the 'wps_local_compress::__construct' function in all versions up to, and including, 6.11.10. This makes it possible for unauthenticated attackers to reset the CDN region and set a malicious URL to deliver images.

The WP Compress – Image Optimizer [All-In-One] plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 6.10.33 via the css parameter. This makes it possible for unauthenticated attackers to read the contents of arbitrary files on the server, which can contain sensitive information.