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Researchers have warned of a critical vulnerability affecting the OpenSSH networking utility that can be exploited to give attackers complete control of Linux and Unix servers with no authentication required.

The vulnerability, tracked as CVE-2024-6387, allows unauthenticated remote code execution with root system rights on Linux systems that are based on glibc, an open source implementation of the C standard library. The vulnerability is the result of a code regression introduced in 2020 that reintroduced CVE-2006-5051, a vulnerability that was fixed in 2006. With thousands if not millions of vulnerable servers populating the Internet, this latest vulnerability could pose a significant risk.

Complete system takeover

“This vulnerability, if exploited, could lead to full system compromise where an attacker can execute arbitrary code with the highest privileges, resulting in a complete system takeover, installation of malware, data manipulation, and the creation of backdoors for persistent access,” wrote Bharat Jogi, the senior director of threat research at Qualys, the security firm that discovered it. “It could facilitate network propagation, allowing attackers to use a compromised system as a foothold to traverse and exploit other vulnerable systems within the organization.”