CVE-1999-0146 in httpd
Summary
by MITRE
The campas CGI program provided with some NCSA web servers allows an attacker to execute arbitrary commands via encoded carriage return characters in the query string, as demonstrated by reading the password file.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability identified as CVE-1999-0146 represents a critical command injection flaw within the campas CGI program distributed with certain NCSA web servers. This vulnerability stems from inadequate input validation and sanitization mechanisms within the CGI script, which processes user-supplied query strings without proper encoding or filtering. The flaw specifically manifests when carriage return characters are embedded within the query string parameters, allowing malicious actors to manipulate the program's execution flow and inject arbitrary commands into the underlying system.
The technical implementation of this vulnerability exploits weaknesses in how the campas CGI program handles input data, particularly around the interpretation of encoded special characters within HTTP query parameters. When an attacker crafts a malicious query string containing encoded carriage return sequences, the program fails to properly sanitize these inputs before processing them, leading to unintended command execution. This type of vulnerability falls under the CWE-77 category of Command Injection, where untrusted data is incorporated into command invocations without proper validation or escaping mechanisms. The attack vector demonstrates how insufficient input validation can enable remote code execution, allowing attackers to bypass normal access controls and potentially gain unauthorized system access.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the capability to execute arbitrary commands on the affected web server with the privileges of the web service account. The demonstration of reading password files highlights the potential for privilege escalation and data exfiltration, as attackers can leverage the command injection to access sensitive system information. This vulnerability directly enables several attack patterns documented in the MITRE ATT&CK framework under the T1059.001 technique for Command and Scripting Interpreter, where adversaries use legitimate system utilities to execute malicious commands. The exposure of password files specifically relates to T1003.001 for OS Credential Dumping, representing a significant compromise of system security and user authentication mechanisms.
Mitigation strategies for CVE-1999-0146 require immediate implementation of input validation and sanitization measures within the affected CGI programs. System administrators should ensure that all user-supplied input is properly escaped or filtered before being processed, particularly around special characters including carriage returns, line feeds, and other control characters. The recommended approach involves implementing strict input validation that rejects or encodes potentially dangerous sequences, along with updating or replacing vulnerable CGI applications with more secure alternatives. Organizations should also consider implementing web application firewalls and input validation rules to prevent such attacks at the network perimeter. Additionally, regular security assessments and vulnerability scanning should be conducted to identify and remediate similar weaknesses in other CGI applications and web server configurations, as this vulnerability type remains relevant in modern web security contexts.