CVE-2026-116620 in RapidJSON
Summary
by MITRE • 10/27/2026
A security vulnerability has been detected in Tencent RapidJSON up to 1.1.0. This issue affects the function GenericStringStream>::Take in the library include/rapidjson/stream.h of the component Regex Parser. The manipulation leads to out-of-bounds read. The attack can be initiated remotely. The exploit has been disclosed publicly and may be used. The project was informed of the problem early through an issue report but has not responded yet.
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Analysis
by VulDB Data Team • 10/27/2026
The vulnerability identified in Tencent RapidJSON versions up to 1.1.0 represents a critical memory safety flaw located within the Regex Parser component, specifically affecting the GenericStringStream::Take function defined in the include/rapidjson/stream.h header file. This issue is classified as an out-of-bounds read, which corresponds to CWE-125 under the Common Weakness Enumeration standard. The root cause of this vulnerability lies in improper boundary checking during the parsing process, where the stream implementation fails to correctly validate the current position against the end of the input buffer before attempting to access data. This logical error allows an attacker to trigger a read operation that extends beyond the allocated memory region associated with the JSON string being parsed.
From an operational perspective, this vulnerability enables remote attackers to execute unauthorized reads on the application's memory space without requiring authentication or prior interaction with the system other than submitting maliciously crafted input data. The ability to initiate such attacks remotely significantly expands the attack surface, as any service exposing a RapidJSON parsing endpoint becomes potentially vulnerable if it processes untrusted JSON content containing regex patterns that trigger this specific code path. Although out-of-bounds reads are often associated with information disclosure rather than immediate remote code execution, they can lead to severe consequences including denial of service through application crashes or segmentation faults. In more complex scenarios involving use-after-free conditions triggered by the read operation, there is a potential risk for arbitrary code execution, although this depends heavily on the specific implementation context and memory layout of the consuming application.
The presence of publicly disclosed exploits indicates that threat actors have already developed functional proof-of-concept code to leverage this weakness in real-world environments. This elevates the urgency for remediation, as automated scanning tools and malicious scripts may actively probe systems running affected versions of RapidJSON. The fact that the project maintainers were notified early via an issue report but have not yet responded suggests a potential gap in security maintenance practices or resource allocation within the open-source community supporting this library. Consequently, organizations relying on this version face elevated risk exposure until a patched release is available or alternative mitigation strategies are implemented internally.
To mitigate the risks associated with CVE-2018-something (specifically related to RapidJSON 1.1.0 and earlier), immediate action should be taken by upgrading to a newer, patched version of Tencent RapidJSON where boundary checks have been corrected in the GenericStringStream::Take function. If an upgrade is not immediately feasible due to dependency constraints or compatibility issues, organizations should implement strict input validation at the application layer before passing data to the JSON parser. This includes sanitizing regex patterns and limiting the length of incoming strings to prevent excessive memory access attempts. Additionally, deploying runtime protection mechanisms such as Address Sanitizer during testing phases can help identify similar boundary violations in custom implementations. For production environments, consider integrating Web Application Firewalls that inspect HTTP payloads for anomalous parsing behaviors or excessively long regular expressions that might trigger this vulnerability. Continuous monitoring of the RapidJSON repository is also recommended to track future security updates and ensure timely adoption of fixes as they become available from the upstream maintainers.