CVE-2020-12762 is a high-severity vulnerability affecting json-c library versions up to 0.14. The vulnerability arises from an integer overflow and subsequent out-of-bounds write in the function printbuf_memappend when processing large JSON files. Specifically, the integer overflow occurs during memory allocation calculations, which leads to insufficient buffer size allocation. When the function attempts to append data to the buffer, it writes beyond the allocated memory bounds, causing memory corruption. This type of vulnerability is classified under CWE-787 (Out-of-bounds Write). Exploitation of this vulnerability requires an attacker to supply a specially crafted large JSON input to an application using the vulnerable json-c library. The CVSS v3.1 score is 7.8, indicating high severity, with the vector AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. This means the attack requires local access (AV:L), low attack complexity (AC:L), no privileges (PR:N), but requires user interaction (UI:R). Successful exploitation can lead to complete compromise of confidentiality, integrity, and availability of the affected system due to memory corruption, potentially enabling arbitrary code execution or denial of service. No known exploits are reported in the wild, and no official patches are linked in the provided data. The vulnerability affects any software components or products that embed or depend on json-c up to version 0.14, which is a widely used JSON parsing and manipulation library in various open-source and commercial projects, especially in Linux-based environments and embedded systems.

For European organizations, the impact of CVE-2020-12762 can be significant, especially those relying on software stacks or embedded systems that use the vulnerable json-c library. This includes telecommunications equipment, network appliances, IoT devices, and certain Linux distributions or applications that parse JSON data locally. Exploitation could allow attackers with local access to escalate privileges, execute arbitrary code, or cause denial of service, potentially disrupting critical infrastructure or business operations. Confidential data processed or stored by affected applications could be exposed or altered. Given the requirement for local access and user interaction, the threat is more pronounced in environments where untrusted users have some level of access or where malicious insiders or compromised accounts exist. The lack of known exploits in the wild reduces immediate risk, but the high severity and potential impact warrant proactive mitigation. European sectors such as finance, healthcare, and critical infrastructure that depend on secure and reliable software components are particularly at risk if they use vulnerable versions of json-c.

To mitigate this vulnerability, European organizations should first identify all software and devices that incorporate json-c library versions up to 0.14. This can be done through software inventory and dependency analysis tools. Since no patch links are provided, organizations should check the official json-c repository or vendor advisories for updated versions beyond 0.14 that address this issue and apply updates promptly. If immediate patching is not feasible, organizations should restrict local access to systems running vulnerable software, enforce strict user privilege management, and monitor for unusual application crashes or memory corruption symptoms. Additionally, implementing application whitelisting and sandboxing can limit the impact of exploitation. For developers, validating and limiting the size of JSON inputs before processing can reduce the risk of triggering the integer overflow. Network segmentation and endpoint protection solutions should be employed to detect and prevent exploitation attempts. Finally, raising user awareness about the risks of processing untrusted JSON files locally can help reduce the chance of successful exploitation requiring user interaction.