CVE-2025-69720: ncurses Buffer Overflow Vulnerability

CVE-2025-69720 Overview

A buffer overflow vulnerability exists in ncurses versions 6.4 and 6.5, specifically within the analyze_string() function located in progs/infocmp.c. This memory corruption flaw could allow an attacker to overwrite adjacent memory regions when processing specially crafted terminal capability strings, potentially leading to application crashes or arbitrary code execution.

Critical Impact

Buffer overflow in the widely-used ncurses terminal handling library affects systems running ncurses v6.4 and v6.5, potentially impacting numerous Linux and Unix-based applications that depend on this library for terminal operations.

Affected Products

• ncurses v6.5
• ncurses v6.4

Discovery Timeline

• 2026-03-19 - CVE-2025-69720 published to NVD
• 2026-03-19 - Last updated in NVD database

Technical Details for CVE-2025-69720

Vulnerability Analysis

The vulnerability resides in the analyze_string() function within the progs/infocmp.c source file. The infocmp utility is used to compare or print compiled terminfo descriptions, and the vulnerable function is responsible for parsing and analyzing terminal capability strings. Due to improper bounds checking when processing input data, a buffer overflow condition can occur when the function handles malformed or excessively long terminal capability strings.

The ncurses library is a fundamental component in Unix-like operating systems, providing APIs for building text-based user interfaces. The infocmp program specifically compares terminfo database entries, making it a target for exploitation when processing untrusted terminfo files or entries.

Root Cause

The root cause of this vulnerability is insufficient boundary validation in the analyze_string() function. When processing terminal capability strings, the function fails to properly verify that the input data length does not exceed the allocated buffer size before copying data. This allows an attacker to supply input that overflows the buffer, corrupting adjacent memory and potentially enabling control flow hijacking.

Attack Vector

An attacker could exploit this vulnerability by crafting a malicious terminfo entry or providing specially crafted input to the infocmp utility. The attack requires the victim to process untrusted terminfo data, either through:

1. Processing a malicious terminfo database file
2. Comparing terminal definitions that include attacker-controlled capability strings
3. Running infocmp against a compromised or malicious terminfo entry

The exploitation mechanism involves supplying an overly long or malformed capability string that triggers the buffer overflow condition in analyze_string(), potentially overwriting critical program data such as return addresses or function pointers.

Additional technical details and proof-of-concept information can be found in the GitHub PoC Repository and the related ncurses bug discussions.

Detection Methods for CVE-2025-69720

Indicators of Compromise

• Unexpected crashes or segmentation faults in applications using ncurses, particularly when running infocmp
• Abnormal memory access patterns in ncurses-dependent applications
• Suspicious terminfo files with unusually long capability string definitions
• Core dumps indicating buffer overflow conditions in the analyze_string() function

Detection Strategies

• Monitor system logs for application crashes related to ncurses or infocmp utility
• Implement file integrity monitoring for terminfo database directories (typically /usr/share/terminfo/ and ~/.terminfo/)
• Deploy memory protection mechanisms such as ASLR and stack canaries to detect exploitation attempts
• Use static analysis tools to identify potentially malicious terminfo files before processing

Monitoring Recommendations

• Enable crash reporting and analyze core dumps for signs of buffer overflow exploitation
• Implement logging for infocmp command execution, especially when processing non-standard terminfo entries
• Monitor for unusual file access patterns in terminfo directories
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation techniques

How to Mitigate CVE-2025-69720

Immediate Actions Required

• Identify all systems running ncurses v6.4 or v6.5 and prioritize them for patching
• Restrict access to the infocmp utility to trusted users where possible
• Avoid processing terminfo files from untrusted sources
• Monitor the ncurses project and distribution repositories for security patches

Patch Information

Users should monitor the official ncurses project and their Linux distribution's security advisories for patch availability. The bug has been discussed on the ncurses bug mailing list, indicating the maintainers are aware of the issue. Apply vendor-provided patches as soon as they become available for your distribution.

Workarounds

• Limit execution of infocmp to trusted users and restrict access via file permissions
• Implement application sandboxing for programs that process terminfo data from untrusted sources
• Use chroot environments or containers when running ncurses utilities against potentially malicious terminfo files
• Enable compiler-based protections (ASLR, stack canaries, FORTIFY_SOURCE) when building ncurses from source

# Restrict infocmp access to root and trusted users
sudo chmod 750 /usr/bin/infocmp
sudo chown root:trusted /usr/bin/infocmp

# Verify installed ncurses version
ncurses6-config --version

# Check for available security updates (Debian/Ubuntu)
apt-cache policy libncurses6