CVE-2026-54897: OHLER55 Oj

Low severity, CVSS 2.1. EPSS: 0.1% chance of exploitation in the next 30 days.

Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. Prior to 3.17.2, Oj::Doc iterators (each_value, each_child, each_leaf) were vulnerable to a heap use-after-free. When a Ruby block yielded during iteration calls doc.close or d.close, the document's heap memory is freed while the C iterator is still running. When control returns from the block, the iterator reads from the freed region, producing a use-after-free accessible from pure Ruby. This issue has been fixed in version 3.17.2.

Affected products

• OHLER55 Oj: before 3.17.2 (fixed in 3.17.2)

Published 2026-07-01. Last modified 2026-07-01.