# CVE-2026-54592: ruby-oj: Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem

CVE-2026-54592 is fixed in ruby-oj on 1 platform, first by DEBIAN-CVE-2026-54592, released July 3, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-54592
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0033
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 1, 2026

## Description

Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.3, Oj::Doc#each_child, when invoked recursively over a deeply nested JSON document, overflows a fixed-size stack buffer and aborts the process, leading to DoS.  In a two-step chain in ext/oj/fast.c, doc_each_child increments doc->where past the where_path[MAX_STACK = 100] array with no bounds check and never restores it (the doc->where-- is missing), so calling each_child recursively from inside the yield block drives doc->where beyond the array. On the next entry  the function copies the path into the 800-byte stack-local buffer save_path[MAX_STACK]  using wlen = doc->where - doc->where_path, so when the previous recursive call left doc->where past where_path[100] the wlen exceeds MAX_STACK and  the memcpy overflows save_path on the C stack; because the Oj::Doc parser imposes no JSON nesting-depth limit (relying on a C-stack pressure check), deeply nested attacker input reaches this path. This issue has been fixed in version 3.17.3.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | ruby-oj Debian 12.15 (bookworm) | 3.14.2-1+deb12u1 | [DEBIAN-CVE-2026-54592](https://patchblox.com/security/data/fix/linux/debian-cve-2026-54592.md) | Jul 3, 2026 |
| Linux | ruby-oj Debian 13.5 (trixie) | 3.16.3-1+deb13u1 | [DEBIAN-CVE-2026-54592](https://patchblox.com/security/data/fix/linux/debian-cve-2026-54592.md) | Jul 3, 2026 |
| Linux | ruby-oj Debian 14 | 3.17.3-1 | [DEBIAN-CVE-2026-54592](https://patchblox.com/security/data/fix/linux/debian-cve-2026-54592.md) | Jul 3, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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