CVE-2019-16166 in cflow
Summary
by MITRE
GNU cflow through 1.6 has a heap-based buffer over-read in the nexttoken function in parser.c.
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Analysis
by VulDB Data Team • 12/18/2023
The vulnerability identified as CVE-2019-16166 represents a critical heap-based buffer over-read flaw within GNU cflow version 1.6 and earlier. This issue manifests in the nexttoken function located within the parser.c source file, where inadequate bounds checking allows for memory access beyond allocated buffer boundaries. The vulnerability occurs during the parsing of input files, specifically when processing certain token sequences that trigger the over-read condition. This type of flaw falls under the category of memory safety issues and can potentially lead to arbitrary code execution or system instability.
The technical implementation of this vulnerability stems from improper memory management within the parser component of GNU cflow. When the nexttoken function processes input data, it fails to validate the length of data being read into a buffer, allowing subsequent memory access operations to extend beyond the allocated memory space. This over-read condition can result in the program accessing uninitialized memory locations, potentially exposing sensitive information or causing unexpected program behavior. The flaw is particularly concerning because it exists in a utility that processes source code files, making it susceptible to exploitation through crafted input files that could be encountered during normal usage scenarios.
From an operational perspective, this vulnerability poses significant risks to systems that rely on GNU cflow for code analysis or documentation generation. Attackers could potentially craft malicious input files that trigger the buffer over-read condition, leading to denial of service conditions or more severe consequences including privilege escalation. The impact extends beyond simple program crashes, as the over-read could expose memory contents that might contain sensitive data or program state information. This vulnerability affects the integrity and availability of systems using GNU cflow, particularly in environments where automated code analysis tools are employed.
Mitigation strategies for CVE-2019-16166 should prioritize immediate patching of affected GNU cflow installations to version 1.7 or later, which contains the necessary fixes for the buffer over-read condition. Organizations should also implement input validation measures when processing untrusted code files through cflow, including restricting file types and implementing sandboxing mechanisms. Security monitoring should be enhanced to detect unusual memory access patterns or potential exploitation attempts. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and could potentially map to ATT&CK technique T1059.007 for execution through shell scripting or code processing utilities. Regular security assessments of development toolchains should include verification of GNU cflow versions to prevent exploitation of this and similar memory safety vulnerabilities.