Bug 2449411 (CVE-2026-32874)

Summary: CVE-2026-32874 UltraJSON: UltraJSON: Denial of Service due to memory leak when parsing large integers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: eglynn, jjoyce, jschluet, lhh, mburns, mgarciac
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in UltraJSON, a fast JSON encoder and decoder. A remote attacker can exploit this vulnerability by providing specially crafted JSON input that contains extremely large integers. When UltraJSON attempts to parse these inputs, it leads to an accumulating memory leak. This excessive memory consumption can ultimately result in a denial of service (DoS) for any service that processes untrusted JSON inputs using UltraJSON.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2449466, 2449468, 2449470, 2449472, 2449474    
Bug Blocks:    

Description OSIDB Bzimport 2026-03-20 03:03:34 UTC 
UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Versions 5.4.0 through 5.11.0 contain an accumulating memory leak in JSON parsing large (outside of the range [-2^63, 2^64 - 1]) integers. The leaked memory is a copy of the string form of the integer plus an additional NULL byte. The leak occurs irrespective of whether the integer parses successfully or is rejected due to having more than sys.get_int_max_str_digits() digits, meaning that any sized leak per malicious JSON can be achieved provided that there is no limit on the overall size of the payload. Any service that calls ujson.load()/ujson.loads()/ujson.decode() on untrusted inputs is affected and vulnerable to denial of service attacks. This issue has been fixed in version 5.12.0.