CVE-2019-11835 in cJSON
Summary
by MITRE
cJSON before 1.7.11 allows out-of-bounds access, related to multiline comments.
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Analysis
by VulDB Data Team • 07/22/2025
The vulnerability identified as CVE-2019-11835 affects the cJSON library version 1.7.10 and earlier, representing a critical out-of-bounds memory access flaw that specifically manifests when processing multiline comments within JSON documents. This issue stems from inadequate input validation and boundary checking mechanisms within the library's comment parsing functionality, creating a potential vector for arbitrary code execution or system compromise.
The technical flaw resides in the library's handling of multiline comments, where the cJSON parser fails to properly validate buffer boundaries when encountering comment blocks that span multiple lines. This weakness allows attackers to craft malicious JSON inputs containing specially formatted multiline comments that trigger memory access violations. The vulnerability specifically impacts the library's ability to accurately track memory allocations and deallocations during comment processing, leading to potential buffer overflows or underflows that could be exploited by remote attackers.
From an operational impact perspective, this vulnerability poses significant risks to applications that rely on cJSON for JSON parsing operations, particularly those handling untrusted input from external sources. The out-of-bounds access can result in application crashes, denial of service conditions, or more severe consequences including arbitrary code execution depending on the specific memory corruption patterns. Systems utilizing cJSON for web applications, API gateways, or any service processing JSON data from potentially malicious sources are particularly vulnerable to exploitation.
The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and CWE-787, covering out-of-bounds write operations. From an attacker's perspective, this flaw maps to ATT&CK technique T1203, involving exploitation of software vulnerabilities, and potentially T1059, covering command and scripting interpreter usage for execution. Organizations should prioritize immediate remediation by upgrading to cJSON version 1.7.11 or later, which includes proper boundary checking mechanisms for multiline comment processing. Additional mitigations include input validation, sandboxing of JSON parsing operations, and implementing network segmentation to limit potential attack surface exposure. Regular security assessments and dependency monitoring should be implemented to prevent similar vulnerabilities in other third-party libraries.