Out-of-Bounds Write Vulnerability in GNU Inetutils Telnetd

CVE-2026-32746

What is CVE-2026-32746?

CVE-2026-32746 is a critical out-of-bounds write vulnerability found in the GNU Inetutils Telnetd, a widely used implementation of the Telnet protocol which facilitates remote communication over a network. This vulnerability arises from the mishandling of buffer size checks within the LINEMODE SLC (Set Local Characters) suboption handler. Specifically, the function responsible for adding SLC suboption characters, add_slc, fails to validate whether the buffer is full before writing data into it. As a result, this flaw can lead to memory corruption, which may allow attackers to execute arbitrary code or disrupt normal operations of the affected systems. Organizations relying on GNU Inetutils Telnetd could face severe consequences, including unauthorized system access and the potential manipulation of sensitive data.

Potential impact of CVE-2026-32746

1. Remote Code Execution: This vulnerability allows attackers to corrupt memory, potentially leading to remote code execution. By exploiting this flaw, a malicious actor could gain control of the affected system, posing major security risks to organizations.

2. System Compromise: Given the nature of the Telnet service, which is often used for remote administration, the exploitation of CVE-2026-32746 can result in complete system compromise. This could facilitate further attacks within the internal network, expanding the potential damage.

3. Denial of Service: The out-of-bounds write could lead to unstable service conditions in Telnetd, resulting in denial of service. This would disrupt legitimate users and operations, leading to significant downtime and productivity loss for organizations dependent on this functionality.

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References