Attackers Exploit Issabel Framework Flaw Enabling Unauthenticated OS Command Execution

Attackers Exploit Issabel Framework Flaw Enabling Unauthenticated OS Command Execution Ravie LakshmananSep 16, 2026Vulnerability / Web Security A critical security flaw in Issabel Framework, a web-based framework for the open-source unified communications PBX software, has come under active exploitation. The vulnerability in question is CVE-2026-89026 (CVSS v3.1 score: 9.8/CVSS v4.0 score: 9.3), which can allow an unauthenticated remote attacker to execute arbitrary operating system (OS) commands by taking advantage of a hard-coded JSON Web Token (JWT) signing key. The Issabel Framework "contains a hard-coded HS256 JWT signing key in the pbxapi index.php file that is identical across every installation, allowing unauthenticated remote attackers to forge valid bearer tokens," VulnCheck said in an alert. "Attackers can use the forged token to…