CVE-2023-29491 in Communications Cloud Native Core Policy
Summary
by MITRE • 04/14/2023
ncurses before 6.4 20230408, when used by a setuid application, allows local users to trigger security-relevant memory corruption via malformed data in a terminfo database file that is found in $HOME/.terminfo or reached via the TERMINFO or TERM environment variable.
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Analysis
by VulDB Data Team • 07/08/2025
The vulnerability identified as CVE-2023-29491 represents a critical security flaw in the ncurses library version 6.4 and earlier, specifically when the library is executed in setuid contexts. This issue stems from inadequate input validation during the processing of terminfo database files, creating a pathway for local attackers to manipulate memory through crafted malicious data. The vulnerability is particularly concerning because it affects applications running with elevated privileges, potentially allowing privilege escalation attacks. The attack vector involves manipulation of terminal information files that are loaded from user-specific directories or through environment variable configurations, making it difficult to predict and prevent without proper input sanitization measures.
The technical root cause of this vulnerability lies in the improper handling of malformed data within terminfo database files during the parsing process. When ncurses processes these files, it fails to validate the structure and content of the terminfo data, allowing attackers to inject malicious sequences that can trigger memory corruption. This memory corruption manifests as buffer overflows, heap corruption, or other exploitable conditions that can be leveraged to execute arbitrary code. The flaw is classified under CWE-121, which deals with stack-based buffer overflow conditions, and CWE-787, which addresses out-of-bounds write vulnerabilities. The vulnerability demonstrates characteristics consistent with the attack pattern described in MITRE ATT&CK technique T1068, where adversaries exploit weaknesses in system libraries to gain elevated privileges.
The operational impact of this vulnerability extends beyond simple local privilege escalation, as it affects any application that utilizes ncurses and runs with setuid permissions. This includes terminal emulators, system administration tools, and various network services that may rely on terminal information for proper operation. Attackers can exploit this vulnerability by placing malicious terminfo files in the $HOME/.terminfo directory or by manipulating the TERMINFO or TERM environment variables to point to crafted data. The consequences range from local privilege escalation to potential system compromise, depending on the specific application context and the privileges of the target process. The vulnerability affects multiple operating systems including Linux distributions, BSD variants, and other Unix-like systems where ncurses is commonly deployed. Organizations running applications that utilize setuid ncurses functionality must urgently address this vulnerability to prevent potential exploitation.
Mitigation strategies for CVE-2023-29491 should focus on immediate patching of affected ncurses versions to 6.4 or later, where the vulnerability has been resolved through enhanced input validation and memory safety improvements. System administrators should also implement restrictive file permissions on terminfo directories and files, ensuring that only authorized users can modify terminal information data. Additionally, monitoring for suspicious file modifications in $HOME/.terminfo directories and environment variable configurations can help detect potential exploitation attempts. The remediation approach aligns with security best practices outlined in NIST SP 800-128 and ISO/IEC 27001 frameworks, which emphasize the importance of maintaining secure library versions and implementing proper access controls. Organizations should also consider implementing application whitelisting policies and runtime protections to prevent unauthorized modifications to critical system libraries. The vulnerability demonstrates the importance of secure coding practices in system libraries and the need for regular security assessments of foundational software components that may be used across multiple applications and services.