# CVE-2026-54592: ohler55 Oj stack buffer overflow in Oj::Doc#each_child

Source: https://junglewise.ai/threats/cve-2026-54592-ohler55-oj-stack-buffer-overflow-in-oj-doc-each-child  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-01. Updated: 2026-07-01  
License: CC BY 4.0 with a link back

CVE-2026-54592 · Severity: high · CVSS 7.5 · Published 2026-07-01

The Oj Ruby gem, a high-performance JSON processing library, contains a flaw in how it handles deeply nested data. An attacker can provide a specially crafted JSON file that causes the application to crash when processed. This results in a denial-of-service (DoS) condition, potentially taking down web services or background workers that rely on this library for data parsing.

Technologies: [oj (RubyGems)](https://junglewise.ai/threats/technologies/oj). Vendors: [RubyGems](https://junglewise.ai/threats/vendors/rubygems).

## Quick answers

**Is CVE-2026-54592 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54592 being exploited in the wild.

**How severe is CVE-2026-54592?** High severity, with a CVSS score of 7.5, published 1 July 2026.

**Which products and versions are affected?** oj (RubyGems) < 3.17.3, ECOSYSTEM:introduced=0,fixed=3.17.3.

**Is there a fix for CVE-2026-54592?** Yes. oj (RubyGems): upgrade to 3.17.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-54592 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-54592?** Check whether you run oj (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- oj (RubyGems): upgrade to 3.17.3 or later

  ```sh
  bundle update oj
  ```


## Technical details

A stack-based buffer overflow exists in 'ext/oj/fast.c' within the 'doc_each_child' function. The vulnerability is triggered when 'each_child' is invoked recursively on a JSON document with a nesting depth exceeding 100. The code fails to perform bounds checking when incrementing 'doc->where' and fails to restore the pointer after the loop. This causes a subsequent 'memcpy' operation to exceed the 800-byte 'save_path' stack buffer. While modern compilers with stack protection (-fstack-protector-strong) will abort the process to prevent code execution, the resulting crash provides a reliable remote denial-of-service vector. The issue is resolved in version 3.17.3 by adding depth validation and proper pointer restoration.

## Affected products

- ohler55 oj < 3.17.3

## Identifiers

- CVE-2026-54592
- GHSA-3m6q-jj5j-38c9

## Timeline

- 2026-06-16: advisory: GitHub Security Advisory published
- 2026-07-01: disclosed: NVD publication date
- 2026-06-16: patched: Fixed in version 3.17.3

## References

- [https://github.com/ohler55/oj/security/advisories/GHSA-3m6q-jj5j-38c9](https://github.com/ohler55/oj/security/advisories/GHSA-3m6q-jj5j-38c9)

## Related threats

- [ohler55 Oj integer overflow in Oj.load heap corruption](https://junglewise.ai/threats/cve-2026-54903-ohler55-oj-integer-overflow-in-oj-load-heap-corruption)
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- [ohler55 Oj Use-After-Free in Oj::Parser GC marking](https://junglewise.ai/threats/cve-2026-54901-ohler55-oj-use-after-free-in-oj-parser-gc-marking)
- [ohler55 Oj heap corruption in Oj::Parser via integer truncation](https://junglewise.ai/threats/cve-2026-54900-ohler55-oj-heap-corruption-in-oj-parser-via-integer-truncation)
- [ohler55 Oj heap use-after-free in Oj::Parser symbol_keys toggle](https://junglewise.ai/threats/cve-2026-54899-ohler55-oj-heap-use-after-free-in-oj-parser-symbol-keys-toggle)