CVE-2018-10754 in ncurses
Summary
by MITRE
In ncurses before 6.1.20180414, there is a NULL Pointer Dereference in the _nc_parse_entry function of tinfo/parse_entry.c. It could lead to a remote denial of service if the terminfo library code is used to process untrusted terminfo data in which a use-name is invalid syntax.
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Analysis
by VulDB Data Team • 02/02/2020
The vulnerability CVE-2018-10754 represents a critical NULL pointer dereference flaw within the ncurses library version 6.1.20180414 and earlier, specifically affecting the _nc_parse_entry function located in tinfo/parse_entry.c. This issue arises when the terminfo library processes untrusted terminfo data containing malformed use-name syntax, creating a potential remote denial of service vector that could be exploited by malicious actors. The flaw demonstrates a classic software security weakness where improper input validation leads to memory access violations that can crash applications using the affected library.
The technical implementation of this vulnerability stems from inadequate error handling within the terminfo parsing mechanism. When ncurses encounters invalid syntax in a use-name field within terminfo database entries, the _nc_parse_entry function fails to properly validate pointer references before dereferencing them, resulting in a NULL pointer dereference condition. This behavior aligns with CWE-476, which categorizes NULL pointer dereference as a common weakness in software development where programs attempt to access memory through a null pointer reference. The vulnerability specifically manifests when the library processes terminal description files that contain malformed entries, particularly those with incorrect use-name declarations that do not conform to expected syntax standards.
The operational impact of CVE-2018-10754 extends beyond simple application crashes to potentially disrupt terminal-based services and applications that depend on ncurses for terminal handling functionality. Attackers could exploit this vulnerability by crafting malicious terminfo data containing invalid use-name syntax and delivering it to systems that process such data, leading to service disruption across multiple applications including shell environments, text editors, and terminal multiplexers. This vulnerability particularly affects systems where ncurses is used to parse user-provided terminal descriptions or where terminal database files are downloaded from untrusted sources, creating a significant risk for network services that rely on proper terminal handling capabilities. The remote nature of this denial of service vulnerability means that attackers need not have local access to exploit the flaw, making it particularly dangerous in networked environments.
Mitigation strategies for CVE-2018-10754 primarily focus on updating to ncurses version 6.1.20180414 or later, which contains the necessary patches to address the NULL pointer dereference condition. System administrators should prioritize patching affected systems and applications that utilize ncurses, particularly those handling untrusted terminal data from external sources. Additionally, implementing proper input validation and sanitization measures when processing terminal description files can provide defense-in-depth protection against similar vulnerabilities. Organizations should also consider restricting access to terminal database files and implementing monitoring for unusual application crashes or service disruptions that could indicate exploitation attempts. This vulnerability demonstrates the importance of maintaining up-to-date system libraries and following secure coding practices that prevent improper pointer handling, aligning with ATT&CK technique T1489 which covers denial of service through resource exhaustion or system instability.