CVE-2025-40930 is a heap-based buffer overflow vulnerability identified in the JSON::SIMD Perl module, specifically in versions prior to 1.07. JSON::SIMD is a Perl library designed to provide fast JSON parsing capabilities using SIMD (Single Instruction, Multiple Data) instructions. The vulnerability arises from an integer buffer overflow during the parsing of specially crafted JSON input. This overflow leads to a segmentation fault (segfault), which can cause the affected application to crash. The root cause is a failure to properly validate or limit the size of certain integer values used to allocate or manage heap buffers, resulting in memory corruption. While the primary observed impact is denial-of-service (DoS) through application crashes, the nature of heap-based buffer overflows can potentially allow attackers to execute arbitrary code or cause other unspecified impacts if exploited further. However, no known exploits are currently reported in the wild. The vulnerability is classified under CWE-122 (Heap-based Buffer Overflow), indicating a memory safety issue that can compromise application stability and security. No official patch or CVSS score is available at this time, and the vulnerability was publicly disclosed on September 8, 2025.

For European organizations, this vulnerability poses a risk primarily to systems and applications that utilize the JSON::SIMD Perl module for JSON parsing. Given the widespread use of Perl in legacy systems, web applications, and backend services, any service relying on vulnerable versions of JSON::SIMD could be susceptible to denial-of-service attacks, leading to service outages or degraded performance. This can affect critical infrastructure, financial services, healthcare systems, and government applications where Perl remains in use. The potential for unspecified impacts beyond DoS, such as remote code execution, although not confirmed, raises concerns about data confidentiality and integrity if exploited. Disruptions caused by crashes could also impact compliance with European data protection regulations (e.g., GDPR) if service availability or data integrity is compromised. The lack of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time.

European organizations should take proactive steps to mitigate this vulnerability beyond generic advice: 1) Inventory and identify all systems and applications using JSON::SIMD, particularly versions prior to 1.07. 2) Where possible, upgrade to JSON::SIMD version 1.07 or later once a patch is released. If no patch is available yet, consider temporarily disabling or replacing JSON::SIMD with alternative JSON parsing libraries that do not have this vulnerability. 3) Implement input validation and sanitization on JSON data before parsing to reduce the risk of processing maliciously crafted JSON payloads. 4) Employ runtime protections such as memory safety tools (e.g., AddressSanitizer) during development and testing to detect buffer overflows. 5) Monitor application logs and system behavior for signs of crashes or abnormal terminations that could indicate exploitation attempts. 6) Restrict network access to services using JSON::SIMD to trusted sources and apply Web Application Firewalls (WAFs) with rules to detect and block suspicious JSON payloads. 7) Prepare incident response plans to quickly address potential DoS incidents related to this vulnerability.