{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-40520/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[{"cvss":7.2,"id":"CVE-2026-40520"}],"_cs_exploited":false,"_cs_products":[],"_cs_severities":["high"],"_cs_tags":["command-injection","freepbx","graphql","cve-2026-40520"],"_cs_type":"advisory","_cs_vendors":[],"content_html":"\u003cp\u003eFreePBX, a widely used open-source PBX (Private Branch Exchange) system, is vulnerable to a command injection flaw within its API module. Specifically, versions 17.0.8 and earlier are affected by CVE-2026-40520. The vulnerability resides in the \u003ccode\u003einitiateGqlAPIProcess()\u003c/code\u003e function, where GraphQL mutation input fields are directly passed to the \u003ccode\u003eshell_exec()\u003c/code\u003e function without proper sanitization or escaping. This allows an authenticated attacker with a valid bearer token to inject and execute arbitrary commands on the underlying host operating system as the web server user. The attack vector involves sending a specially crafted GraphQL \u003ccode\u003emoduleOperations\u003c/code\u003e mutation containing backtick-wrapped commands within the \u003ccode\u003emodule\u003c/code\u003e field. Successful exploitation grants the attacker the ability to compromise the FreePBX server and potentially pivot to other internal systems.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eThe attacker authenticates to the FreePBX API using a valid bearer token.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a GraphQL \u003ccode\u003emoduleOperations\u003c/code\u003e mutation request.\u003c/li\u003e\n\u003cli\u003eWithin the \u003ccode\u003emodule\u003c/code\u003e field of the mutation, the attacker injects a command using backticks (e.g., \u003ccode\u003e\\\u003c/code\u003eid` `).\u003c/li\u003e\n\u003cli\u003eThe attacker sends the malicious GraphQL request to the \u003ccode\u003e/api\u003c/code\u003e endpoint.\u003c/li\u003e\n\u003cli\u003eThe \u003ccode\u003einitiateGqlAPIProcess()\u003c/code\u003e function processes the request without proper sanitization.\u003c/li\u003e\n\u003cli\u003eThe injected command is passed to the \u003ccode\u003eshell_exec()\u003c/code\u003e function within \u003ccode\u003eApi.class.php\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe \u003ccode\u003eshell_exec()\u003c/code\u003e function executes the injected command on the FreePBX server as the web server user (e.g., \u003ccode\u003ewww-data\u003c/code\u003e, \u003ccode\u003eapache\u003c/code\u003e).\u003c/li\u003e\n\u003cli\u003eThe attacker gains arbitrary command execution on the server.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this command injection vulnerability (CVE-2026-40520) allows an attacker to execute arbitrary commands on the FreePBX server with the privileges of the web server user. This can lead to complete compromise of the PBX system, allowing the attacker to eavesdrop on calls, modify call routing, steal sensitive data, install malware, and potentially pivot to other systems on the network. Given the critical role of PBX systems in business communications, a successful attack can disrupt operations, damage reputation, and result in significant financial losses.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade the FreePBX API module to a version greater than 17.0.8 to patch CVE-2026-40520.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eDetect FreePBX GraphQL Command Injection\u003c/code\u003e to identify exploitation attempts by detecting backticks in GraphQL mutation requests.\u003c/li\u003e\n\u003cli\u003eMonitor web server logs for POST requests to the \u003ccode\u003e/api\u003c/code\u003e endpoint containing GraphQL mutations with backtick-wrapped commands to detect command injection attempts.\u003c/li\u003e\n\u003cli\u003eImplement input validation and sanitization measures for all GraphQL input fields to prevent command injection vulnerabilities.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-04-21T13:16:20Z","date_published":"2026-04-21T13:16:20Z","id":"/briefs/2026-04-freepbx-command-injection/","summary":"FreePBX api module version 17.0.8 and prior contain a command injection vulnerability in the initiateGqlAPIProcess() function, allowing authenticated users to execute arbitrary commands via crafted GraphQL mutations.","title":"FreePBX API Module Command Injection Vulnerability (CVE-2026-40520)","url":"https://feed.craftedsignal.io/briefs/2026-04-freepbx-command-injection/"}],"language":"en","title":"CraftedSignal Threat Feed — Cve-2026-40520","version":"https://jsonfeed.org/version/1.1"}