{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-6555/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[{"cvss":9.8,"id":"CVE-2026-6555"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["WP Client plugin \u003c= 2.0.0"],"_cs_severities":["critical"],"_cs_tags":["cve","wordpress","file-upload","rce","CVE-2026-6555"],"_cs_type":"advisory","_cs_vendors":["WordPress"],"content_html":"\u003cp\u003eThe ProSolution WP Client plugin, a popular WordPress plugin, is susceptible to an arbitrary file upload vulnerability, identified as CVE-2026-6555. This vulnerability affects versions up to and including 2.0.0. The core issue lies in how the plugin handles file uploads. It inadequately validates uploaded files, particularly when multiple files are uploaded simultaneously. Specifically, the plugin only validates the extension and MIME type of the first file in the upload array. However, it processes and uploads all files within the array to a web-accessible directory. This flaw allows unauthenticated attackers to bypass security checks by prepending a valid file to the array. This vulnerability can lead to remote code execution (RCE) on the targeted WordPress site, as attackers can inject malicious PHP scripts.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn unauthenticated attacker identifies a WordPress site using a vulnerable version (\u0026lt;= 2.0.0) of the ProSolution WP Client plugin.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a malicious HTTP POST request to the file upload endpoint of the plugin, typically located at /wp-content/plugins/wp-client/upload.php or a similar path.\u003c/li\u003e\n\u003cli\u003eThe POST request includes a multipart/form-data payload containing an array of files. The first file is a benign file with a valid extension (e.g., .jpg, .png) and MIME type.\u003c/li\u003e\n\u003cli\u003eThe subsequent file in the array is a malicious PHP script with a .php extension, disguised or named to evade basic detection.\u003c/li\u003e\n\u003cli\u003eThe server-side validation process checks only the first file\u0026rsquo;s extension and MIME type, passing it.\u003c/li\u003e\n\u003cli\u003eThe plugin processes and uploads all files in the array to the web-accessible directory, such as /wp-content/uploads/wp-client/.\u003c/li\u003e\n\u003cli\u003eThe attacker then sends an HTTP request to the uploaded malicious PHP script (e.g., /wp-content/uploads/wp-client/malicious.php).\u003c/li\u003e\n\u003cli\u003eThe server executes the PHP script, granting the attacker remote code execution on the server, enabling them to perform actions like data exfiltration, defacement, or further exploitation.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this vulnerability allows unauthenticated attackers to execute arbitrary code on the targeted WordPress server. This can lead to complete compromise of the website, including data theft, defacement, or use of the server as a platform for further attacks. Given the widespread use of WordPress and the popularity of the WP Client plugin, a large number of websites are potentially vulnerable. The impact of a successful attack is high, potentially leading to significant financial and reputational damage.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade the ProSolution WP Client plugin to a version greater than 2.0.0 to patch CVE-2026-6555.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026ldquo;Detect CVE-2026-6555 Exploitation Attempt — ProSolution WP Client Arbitrary File Upload\u0026rdquo; to your SIEM to detect potential exploitation attempts based on HTTP POST requests to the plugin\u0026rsquo;s upload endpoint.\u003c/li\u003e\n\u003cli\u003eMonitor web server logs for HTTP requests to the /wp-content/uploads/wp-client/ directory containing PHP files, which could indicate successful exploitation of CVE-2026-6555.\u003c/li\u003e\n\u003cli\u003eImplement strict file extension and MIME type validation on all file upload endpoints, ensuring that all files in an array are validated, not just the first one.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-20T02:17:55Z","date_published":"2026-05-20T02:17:55Z","id":"https://feed.craftedsignal.io/briefs/2026-05-cve-2026-6555-wp-client-upload/","summary":"The ProSolution WP Client plugin for WordPress is vulnerable to arbitrary file upload (CVE-2026-6555) due to a validation mismatch, allowing unauthenticated attackers to upload malicious PHP files leading to remote code execution.","title":"ProSolution WP Client Plugin Arbitrary File Upload Vulnerability (CVE-2026-6555)","url":"https://feed.craftedsignal.io/briefs/2026-05-cve-2026-6555-wp-client-upload/"}],"language":"en","title":"CraftedSignal Threat Feed — CVE-2026-6555","version":"https://jsonfeed.org/version/1.1"}