CVE-2026-54902 Oj: Use-After-Free in Oj::Parser SAJ Long Key Callback

Oj Optimized JSON is a JSON parser and Object marshaller packaged as a Ruby gem. Prior to version 3.17.2, is vulnerable to Use-After-Free when in SAJ mode. The Oj::Parser does not protect cached object keys ≥ 35 bytes from garbage collection, and a Ruby callback that triggers GC inside hashend ca...

CVE-2026-54902

CVE-2026-54902 affects the Ruby gem Oj (Optimized JSON). In SAJ mode prior to 3.17.2, the parser’s key caching can be GC’d while the C parser still references it, causing a Use-After-Free and a segfault when a freed VALUE is accessed. The issue is fixed in version 3.17.2. Exploitation details are...

Oj - Use-After-Free in 'Oj::Parser' SAJ Long Key Callback

Summary Oj::Parser in SAJ mode does not protect cached object keys ≥ 35 bytes from garbage collection. A Ruby callback that triggers GC inside hashend can cause the key string to be reclaimed while the C parser still holds a pointer to it. The subsequent access to the freed string VALUE results i...