Bug 2449400 (CVE-2026-32875)

Summary: CVE-2026-32875 ultrajson: UltraJSON: Denial of Service via large indent parameter in JSON serialization
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: aprice, eglynn, jjoyce, jpretori, jsamir, jschluet, lhh, mburns, mgarciac, oezr
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. This vulnerability allows a remote attacker to cause a denial of service (DoS) by providing a specially crafted large positive or negative indent value to the JSON serialization functions. This can lead to a buffer overflow, causing the Python interpreter to crash, or an infinite loop, making the application unresponsive. The issue stems from an integer overflow or underflow during memory allocation for indentation.
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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: 2449465, 2449467, 2449469, 2449471, 2449473    
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Description OSIDB Bzimport 2026-03-20 03:02:55 UTC 
UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Versions 5.10 through 5.11.0 are vulnerable to buffer overflow or infinite loop through large indent handling. ujson.dumps() crashes the Python interpreter (segmentation fault) when the product of the indent parameter and the nested depth of the input exceeds INT32_MAX. It can also get stuck in an infinite loop if the indent is a large negative number. Both are caused by an integer overflow/underflow whilst calculating how much memory to reserve for indentation. And both can be used to achieve denial of service. To be vulnerable, a service must call ujson.dump()/ujson.dumps()/ujson.encode() whilst giving untrusted users control over the indent parameter and not restrict that indentation to reasonably small non-negative values. A service may also be vulnerable to the infinite loop if it uses a fixed negative indent. An underflow always occurs for any negative indent when the input data is at least one level nested but, for small negative indents, the underflow is usually accidentally rectified by another overflow. This issue has been fixed in version 5.12.0.