CVE-2017-0899 in RubyGems
Summary
by MITRE
RubyGems version 2.6.12 and earlier is vulnerable to maliciously crafted gem specifications that include terminal escape characters. Printing the gem specification would execute terminal escape sequences.
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Analysis
by VulDB Data Team • 05/10/2026
CVE-2017-0899 represents a terminal escape sequence injection vulnerability affecting RubyGems versions 2.6.12 and earlier, which falls under the CWE-116 classification for improper encoding or normalization of data. This vulnerability stems from the insufficient sanitization of gem specification metadata, particularly when displaying gem information in terminal environments. The flaw allows attackers to craft malicious gem specifications containing terminal escape characters such as ANSI escape codes that can manipulate terminal behavior when the gem information is printed or displayed. When RubyGems processes these crafted specifications, the terminal escape sequences embedded within the metadata can execute commands or alter terminal display properties, potentially leading to information disclosure or terminal manipulation attacks.
The technical exploitation of this vulnerability occurs through the manipulation of gem specification files, specifically targeting the metadata fields that are displayed when users interact with gem information. Attackers can include escape sequences in fields such as gem descriptions, authors, or other displayable metadata within the gemspec file. When legitimate users or automated systems query or display gem information, these sequences execute within the terminal context, potentially allowing attackers to perform actions like clearing the screen, changing text colors, or even executing commands that bypass normal terminal security restrictions. This vulnerability operates at the intersection of input validation and output sanitization, where the system fails to properly sanitize user-provided data before rendering it in a terminal environment.
The operational impact of CVE-2017-0899 extends beyond simple display manipulation, as it can be leveraged in broader attack scenarios within terminal-based environments. An attacker could craft a malicious gem that, when displayed, executes terminal commands or reveals sensitive information through color manipulation or screen clearing operations. This vulnerability is particularly concerning in automated build environments or continuous integration systems where gem information is frequently displayed and processed. The attack surface includes scenarios where developers or system administrators might unknowingly interact with malicious gems, leading to potential information disclosure or terminal state manipulation. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation through terminal manipulation.
Mitigation strategies for CVE-2017-0899 focus on both immediate remediation and long-term architectural improvements. The primary fix involves upgrading RubyGems to version 2.6.13 or later, where proper sanitization of terminal escape sequences has been implemented. Organizations should also implement strict gem verification processes and maintain updated gem repositories to prevent the introduction of malicious specifications. Additional defensive measures include configuring terminal environments to sanitize input before display, implementing proper input validation for gem metadata, and establishing secure development practices that include code review processes for gem specifications. Security teams should monitor for suspicious gem activity and consider implementing automated scanning of gem repositories for potentially malicious specifications. The vulnerability highlights the importance of proper data sanitization in terminal environments and demonstrates how seemingly benign metadata fields can become attack vectors when not properly validated against terminal escape sequence injection patterns.