CVE-2016-10749 in cJSON
Summary
by MITRE
parse_string in cJSON.c in cJSON before 2016-10-02 has a buffer over-read, as demonstrated by a string that begins with a " character and ends with a \ character.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 07/22/2025
The vulnerability identified as CVE-2016-10749 resides within the cJSON library, a lightweight JSON parsing and generation library widely used in embedded systems and applications requiring efficient JSON processing. This specific flaw manifests in the parse_string function located within the cJSON.c source file, which operates before the library version released on October 2, 2016. The issue constitutes a classic buffer over-read condition that occurs when processing malformed JSON strings, creating potential security risks for applications that rely on cJSON for JSON data handling. The vulnerability is particularly concerning because JSON parsing is fundamental to modern application communication, making this flaw potentially exploitable across numerous software systems.
The technical implementation of this vulnerability stems from inadequate boundary checking within the parse_string function when processing JSON strings that begin with a double quote character and end with a backslash character. When cJSON encounters such malformed input, the parsing logic fails to properly validate buffer boundaries during string extraction, leading to memory access beyond the allocated buffer limits. This over-read condition occurs because the parser does not adequately handle the escape sequence termination scenario, where a backslash character at the end of a string potentially signals an incomplete escape sequence that should trigger an error condition rather than allowing memory access beyond intended boundaries. The flaw specifically affects how the parser handles the transition from string content to termination, creating a scenario where memory locations beyond the string buffer are accessed and potentially read.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can enable various attack vectors including information disclosure, application crashes, and potentially remote code execution depending on the application context and memory layout. When an application using the vulnerable cJSON library processes maliciously crafted JSON input containing strings with the specific pattern of starting with a quote and ending with a backslash, the over-read can expose sensitive data from adjacent memory locations or cause unpredictable application behavior. This vulnerability is particularly dangerous in embedded systems or IoT devices where cJSON is commonly deployed, as these environments often lack robust memory protection mechanisms that might otherwise prevent exploitation. The issue demonstrates poor input validation practices and highlights the importance of proper buffer boundary checking in parsing libraries that handle untrusted data.
Mitigation strategies for CVE-2016-10749 primarily involve updating to a patched version of the cJSON library released after October 2, 2016, which addresses the buffer over-read condition through proper boundary validation in the parse_string function. Organizations should conduct thorough inventory assessments to identify all systems and applications utilizing vulnerable versions of cJSON, as this library is embedded in numerous software products across different platforms. The fix implemented by the maintainers typically involves adding proper validation checks before accessing memory locations beyond the string buffer boundaries, ensuring that the parser correctly handles edge cases including incomplete escape sequences and malformed string terminations. From a cybersecurity perspective, this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and may be relevant to ATT&CK technique T1059.007 for command and scripting interpreter usage in exploitation contexts. System administrators should also consider implementing input validation layers and sandboxing mechanisms to reduce the potential impact of similar vulnerabilities in other parsing components within their application stacks.