CVE-2026-54901 — Oj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class…
Published: 2026-06-30 · CVSS: 6.3 · CVSS 4.0
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj::Parser in usual mode does not mark array_class and hash_class references during garbage collection, leading to Use-After-Free. If GC runs after the class is assigned but before a parse, the class object is reclaimed, leaving the parser holding a dangling VALUE. The subsequent parse call dereferences the freed object, producing a segfault. This issue has been fixed in version 3.17.2.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7