CVE-2015-8863 in jq
Summary
by MITRE
Off-by-one error in the tokenadd function in jv_parse.c in jq allows remote attackers to cause a denial of service (crash) via a long JSON-encoded number, which triggers a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 11/07/2024
The vulnerability identified as CVE-2015-8863 represents a critical heap-based buffer overflow in the jq command-line JSON processor, specifically within the tokenadd function located in jv_parse.c. This flaw arises from an off-by-one error that occurs when processing long JSON-encoded numbers, creating a condition where the application fails to properly validate input boundaries during parsing operations. The issue manifests when jq encounters JSON data containing excessively long numeric values, causing the parser to write beyond the allocated memory buffer and potentially leading to application crashes or unpredictable behavior.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within the JSON parsing logic. When jq processes a JSON document containing a very long number, the tokenadd function attempts to store this value in a buffer without proper boundary checking. This off-by-one error creates a situation where one additional byte of data is written beyond the intended buffer limits, resulting in heap corruption that can trigger memory allocation failures or segmentation faults. The vulnerability specifically affects the parsing phase of JSON data processing, making it exploitable during any operation that involves parsing JSON input containing extended numeric sequences.
From an operational impact perspective, this vulnerability enables remote attackers to execute denial of service attacks against systems running jq or applications that utilize jq for JSON processing. The crash condition can be reliably triggered by crafting malicious JSON input containing excessively long numeric values, potentially affecting web applications, API endpoints, or automated systems that depend on jq for data processing. The vulnerability's remote exploitability means that attackers can leverage this flaw without requiring local system access, making it particularly dangerous in networked environments where jq is exposed to untrusted input sources. This type of vulnerability can significantly impact system availability and reliability, especially in environments where jq is used as a core component of data processing pipelines or automated workflows.
Security practitioners should implement multiple layers of mitigation to address this vulnerability effectively. The primary recommendation involves upgrading to a patched version of jq that resolves the off-by-one error in the tokenadd function, ensuring that all input validation and buffer boundary checks are properly implemented. Additionally, input sanitization measures should be deployed at system boundaries to filter or truncate excessively long numeric values before they reach the jq parser. Network-level protections such as rate limiting and input validation firewalls can help prevent exploitation attempts, while monitoring systems should be configured to detect unusual application crash patterns that may indicate exploitation attempts. This vulnerability aligns with CWE-121 heap-based buffer overflow and can be mapped to ATT&CK technique T1499.004 for denial of service attacks, emphasizing the importance of proper memory management and input validation in preventing such critical security flaws.