CVE-1999-1186 in Rxvt
Summary
by MITRE
rxvt, when compiled with the PRINT_PIPE option in various Linux operating systems including Linux Slackware 3.0 and RedHat 2.1, allows local users to gain root privileges by specifying a malicious program using the -print-pipe command line parameter.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability identified as CVE-1999-1186 affects the rxvt terminal emulator when compiled with the PRINT_PIPE option, presenting a significant privilege escalation risk in affected Linux distributions including Slackware 3.0 and RedHat 2.1. This flaw resides in the command line parameter handling mechanism of the terminal application, specifically the -print-pipe option that was designed to facilitate printing functionality through pipe mechanisms. The vulnerability stems from insufficient input validation and improper privilege handling within the rxvt application's execution flow, creating an exploitable condition where local users can manipulate the program's behavior to execute arbitrary code with elevated privileges. The issue represents a classic case of improper input sanitization and privilege management that directly violates security principles outlined in CWE-78 and CWE-20, where command injection vulnerabilities occur due to inadequate validation of user-supplied data.
The technical exploitation of this vulnerability occurs when a local attacker leverages the -print-pipe command line parameter to specify a malicious program or script that gets executed with root privileges. When rxvt is compiled with the PRINT_PIPE option, it accepts user input through this parameter and passes it directly to system execution functions without proper privilege separation or input filtering. This creates a scenario where the terminal emulator, running with elevated privileges to perform printing operations, inadvertently executes attacker-controlled code through the pipe mechanism. The flaw operates at the application level where user input is not properly validated or sanitized before being processed, allowing for arbitrary command execution that bypasses normal privilege boundaries. The vulnerability manifests as a privilege escalation vector that transforms local user access into root-level access, fundamentally compromising system security.
The operational impact of CVE-1999-1186 extends beyond simple privilege escalation, representing a critical weakness in the security model of affected systems. This vulnerability enables attackers to execute arbitrary code with root privileges, potentially leading to complete system compromise, data exfiltration, or persistent backdoor installation. The affected systems, particularly those running Slackware 3.0 and RedHat 2.1, were widely deployed in enterprise and server environments where terminal emulators are commonly used. The exploitation of this vulnerability can be categorized under ATT&CK technique T1068, which addresses privilege escalation through local exploits, and T1059, which covers command and scripting interpreter usage. The vulnerability's persistence in these older distributions highlights the importance of proper input validation and privilege separation in security-critical applications, as the flaw exists due to inadequate design considerations for handling user-supplied parameters that are intended for system-level operations.
Mitigation strategies for CVE-1999-1186 require immediate action to address the root cause through proper application configuration and system hardening. The primary solution involves either disabling the PRINT_PIPE option during rxvt compilation or ensuring that the application runs with minimal required privileges. System administrators should implement proper input validation mechanisms and avoid compiling applications with unnecessary privileged features. The vulnerability can be addressed through patching the rxvt application to properly sanitize command line parameters or by removing the PRINT_PIPE functionality entirely from production systems. Additionally, implementing privilege separation techniques and ensuring that applications do not execute with elevated privileges unless absolutely necessary aligns with security best practices outlined in the principle of least privilege. Organizations should also consider monitoring for unauthorized modifications to terminal emulator configurations and implementing proper access controls to prevent local users from exploiting such vulnerabilities. The remediation efforts should include updating to patched versions of rxvt, conducting security audits of terminal applications, and ensuring that all system components follow secure coding practices to prevent similar privilege escalation vectors from being introduced in the future.