UltraJSON has an integer overflow handling large indent leads to buffer overflow or infinite loop

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2026-32875
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-20 02:16:35 UTC
Updated2026-07-15 02:20:01 UTC
DescriptionUltraJSON 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.004690000 probability, percentile 0.375390000 (date 2026-07-16)

Problem Types: CWE-190 | CWE-787 | CWE-835 | CWE-190 CWE-190: Integer Overflow or Wraparound | CWE-787 CWE-787: Out-of-bounds Write | CWE-835 CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') | CWE-190 Integer Overflow or Wraparound

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Ultrajson Project Ultrajson All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Ultrajson Ultrajson affected >= 5.1.0, < 5.12.0 Not specified
ADP Red Hat Red Hat OpenStack Platform 16.2 Not specified Not specified
ADP Red Hat Red Hat OpenStack Platform 17.1 Not specified Not specified
ADP Red Hat Red Hat OpenStack Platform 18.0 Not specified Not specified

References

ReferenceSourceLinkTags
github.com/ultrajson/ultrajson/issues/700 [email protected] github.com Issue Tracking
access.redhat.com/security/cve/CVE-2026-32875 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
github.com/ultrajson/ultrajson/commit/486bd4553dc471a1de11613bc7347a6b31... [email protected] github.com Patch
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32875.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
github.com/ultrajson/ultrajson/security/advisories/GHSA-c8rr-9gxc-jprv [email protected] github.com Exploit, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
ADP2026-03-20T03:02:30.994ZReported to Red Hat.
ADP2026-03-20T01:35:23.362ZMade public.
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