CVE-2026-54502: OHLER55 Oj

Medium severity, CVSS 6.3. EPSS: 0.3% chance of exploitation in the next 30 days.

Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, Oj.dump is vulnerable to a stack-based buffer overflow when a large :indent value is provided by the developer. fill_indent in dump.h calls memset(indent_str, ' ', (size_t)opts->indent) without validating the size. When opts->indent is set to INT_MAX (2,147,483,647), the (size_t) cast preserves the large value and memset writes 2 GB into the stack-allocated out buffer (4,184 bytes), corrupting the stack and crashing the process. 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.