Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.

A flaw was found in Oj, a Ruby gem for JSON parsing. When processing a specially crafted JSON object key of a specific length (65,535 bytes) in usual mode with create_id enabled, an integer truncation vulnerability occurs. This leads to a negative size being passed to the `memcpy` function, causing heap memory corruption and crashing the process. A remote attacker could exploit this to cause a denial of service.

Red Hat's only product shipping the Oj Ruby gem (Compliance Backend) already includes version 3.17.3, which contains the fix for this vulnerability. No Red Hat products are affected. https://www.cve.org/CVERecord?id=CVE-2026-54900 https://nvd.nist.gov/vuln/detail/CVE-2026-54900 https://github.com/ohler55/oj/security/advisories/GHSA-9cv6-qcjw-4grx