Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2026-32875 is a high-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Ultrajson Project Ultrajson. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 38th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-2 (Flaw Remediation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-32875 affects UltraJSON, a fast JSON encoder and decoder written in pure C with bindings for Python 3.7 and later. Versions 5.10 through 5.11.0 are vulnerable to buffer overflow or infinite loop conditions triggered by large indent values in functions like ujson.dumps(), ujson.dump(), and ujson.encode(). The issues stem from integer overflow or underflow during memory reservation calculations for indentation: a product of the indent parameter and input nested depth exceeding INT32_MAX causes a segmentation fault and Python interpreter crash, while a large negative indent leads to an infinite loop. These flaws, published on 2026-03-20, are classified under CWE-190 (Integer Overflow or Wraparound), CWE-787 (Out-of-bounds Write), and CWE-835 (Loop with Unreachable Exit Condition), with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Any network-accessible service using vulnerable UltraJSON versions can be exploited remotely without authentication or user interaction if it passes untrusted user input as the indent parameter without restricting it to small non-negative values. Attackers can supply a large positive indent combined with deeply nested JSON to trigger the overflow and crash the interpreter, or a large negative indent to induce an infinite loop, both resulting in denial of service. Services using fixed negative indents are also at risk if the input has at least one level of nesting, as underflow occurs reliably in such cases.
Mitigation is available in UltraJSON version 5.12.0, which addresses the integer overflow and underflow issues. Security practitioners should upgrade to this version immediately and validate or sanitize the indent parameter to reasonable non-negative values in applications handling untrusted input. Relevant advisories and fixes are detailed in the GitHub security advisory (GHSA-c8rr-9gxc-jprv), issue tracker (#700), and the fixing commit (486bd4553dc471a1de11613bc7347a6b318e37ea).
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-13444
Vulnerability Data
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)…
more
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
—
V5.2.6
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds integer overflow defects before deployment.
Flaw remediation processes identify and correct infinite-loop defects reported from testing or operations.
Requiring documented secure-development standards and tools can mandate bounds-checked coding practices that avoid the weakness.
Secure engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer overflow during calculation.
Input validation enforces bounds on values before arithmetic, stopping the conditions that trigger overflow or wraparound.
Memory-protection mechanisms limit the exploitability and blast radius of a successful out-of-bounds write.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.
Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.
Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect integer overflows before release.
Secure SDLC mandates input validation and arithmetic checks that prevent integer overflows.
Application security requirements include bounds checking and safe arithmetic to avoid overflow conditions.
Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.
Secure coding standards explicitly forbid unsafe integer operations and mandate overflow-safe constructs.
Change management can enforce review gates that catch unsafe memory operations before deployment.