CVE-2020-36429: 
NixOS vulnerability analysis and mitigation

Variant_encodeJson in open62541 versions 1.x before 1.0.4 contains a vulnerability that results in an out-of-bounds write when processing large recursion depths (CVE Mitre, NVD). The vulnerability was discovered through OSS-Fuzz testing and was fixed in version 1.0.4.

The vulnerability occurs in the Variant_encodeJson function when processing JSON encoding with deep recursion. The issue manifests as an UNKNOWN WRITE crash type when the recursion depth exceeds the maximum allowed limit. The fix involved adding proper checks for maximum recursion depth in multiple places throughout the code (OSS-Fuzz Report, GitHub Fix).

When exploited, this vulnerability could lead to out-of-bounds write operations, potentially causing memory corruption or program crashes. The severity was classified as HIGH according to the ecosystem-specific rating (OSS-Fuzz Vuln).

The vulnerability was fixed in open62541 version 1.0.4 by implementing proper recursion depth checks in various locations throughout the code. Users should upgrade to version 1.0.4 or later to address this security issue (GitHub Fix).