Ruby oj: Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. (CVE-2026-54903)
Description
Oj (Optimized JSON) is a Ruby gem used for JSON parsing and object marshalling. Versions prior to 3.17.2 contain a vulnerability in the Oj.load function that leads to heap corruption when parsing JSON strings longer than 2 GB. This is caused by an integer overflow in the buf_append_string function, resulting in out-of-bounds memory copying and process crashes. The issue has been fixed in version 3.17.2.
CVSS v4.0
Affected software
pkg:deb/ubuntu/ruby-oj?arch=source&distro=trustypkg:deb/ubuntu/ruby-oj?arch=source&distro=xenialpkg:deb/ubuntu/ruby-oj?arch=source&distro=bionicpkg:deb/ubuntu/ruby-oj?arch=source&distro=focalpkg:deb/ubuntu/ruby-oj?arch=source&distro=jammypkg:deb/ubuntu/ruby-oj?arch=source&distro=noblepkg:deb/ubuntu/ruby-oj?arch=source&distro=questingpkg:deb/ubuntu/ruby-oj?arch=source&distro=stonkingpkg:deb/ubuntu/ruby-oj?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in Oj (Optimized JSON) affects versions prior to 3.17.2. When parsing JSON strings larger than 2 GB, an integer overflow occurs in the buf_append_string function (buf.h:61), which converts the string length to a large negative size_t value. This causes memcpy to copy an excessive amount of data out of bounds, leading to heap corruption and process crashes. This flaw is triggered by the Oj.load method. The issue has been addressed and fixed in version 3.17.2.
Potential Impact
Exploitation of this vulnerability can cause the affected process to crash and corrupt adjacent heap memory. This may lead to denial of service or potentially other memory corruption consequences. There is no indication of code execution or data disclosure from the provided information.
Mitigation Recommendations
Upgrade to Oj version 3.17.2 or later, where this vulnerability has been fixed. No other mitigations are specified or required.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-54903
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:14.04:LTS","Ubuntu:16.04:LTS","Ubuntu:18.04:LTS","Ubuntu:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:26.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad3f5f52cdf04f656663532
Added to database: 10/17/2026, 22:25:57 UTC
Last enriched: 10/18/2026, 00:47:09 UTC
Last updated: 10/18/2026, 00:47:09 UTC
Views: 2
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