CVE-2016-6830 in Scheme
Summary
by MITRE
The "process-execute" and "process-spawn" procedures in CHICKEN Scheme used fixed-size buffers for holding the arguments and environment variables to use in its execve() call. This would allow user-supplied argument/environment variable lists to trigger a buffer overrun. This affects all releases of CHICKEN up to and including 4.11 (it will be fixed in 4.12 and 5.0, which are not yet released).
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Analysis
by VulDB Data Team • 04/20/2025
The vulnerability identified as CVE-2016-6830 represents a critical buffer overflow condition within the CHICKEN Scheme implementation that directly impacts the security of systems utilizing this interpreted language. This flaw exists in the core process execution mechanisms of the software, specifically within the "process-execute" and "process-spawn" procedures that handle system call operations through the execve() function. The vulnerability stems from the use of fixed-size buffers to store command-line arguments and environment variables that are passed to these system calls, creating an exploitable condition where user-supplied input can exceed the predetermined buffer limits.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and more specifically with CWE-122, which addresses stack-based buffer overflow scenarios. The flaw manifests when the CHICKEN Scheme interpreter attempts to execute external processes through its process management functions, as these functions do not properly validate the length of argument lists or environment variable collections before copying them into fixed-size memory buffers. This design oversight allows attackers to craft malicious input sequences that deliberately overflow these buffers, potentially leading to arbitrary code execution or system compromise.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it provides a potential pathway for privilege escalation and remote code execution within systems running vulnerable versions of CHICKEN Scheme. When exploited, the buffer overflow could allow attackers to overwrite adjacent memory regions including return addresses, function pointers, or other critical control data structures within the process execution context. This represents a significant concern for environments where CHICKEN Scheme is used to execute untrusted code or where the interpreter runs with elevated privileges, as the vulnerability could be leveraged to bypass security controls and gain unauthorized access to system resources.
The affected versions of CHICKEN Scheme, specifically releases up to and including version 4.11, represent a substantial attack surface given the widespread use of this Scheme implementation in various applications and embedded systems. The vulnerability affects both the process-execute and process-spawn procedures, indicating that any application utilizing these functions for external process management is potentially at risk. The fix for this vulnerability was implemented in the upcoming releases 4.12 and 5.0, which properly implement dynamic buffer allocation or length validation mechanisms to prevent the overflow conditions. Security practitioners should prioritize updating systems running vulnerable versions to mitigate potential exploitation, as the ATT&CK framework categorizes this as a privilege escalation technique through memory corruption, specifically targeting process injection and execution control mechanisms within interpreted language environments.