CVE•Published 2026-05-27•Modified 2026-06-02•0 articles on news•5 live references•NVD data

CVE-2026-44660Ultrajson_project · Ultrajson

Vulnerability data via NVD (ingested)

CVSS v3.1

7.5

HIGH

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

EPSS percentile

—

Weaknesses (CWE)

CWE-401Missing Release of Memory after Effective Lifetime

Description

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.12.1, when ujson.dump() writes to a file-like object and the write operation raises an exception, the serialized JSON string object is not decremented, leaking memory. Each failed write operation leaks the full size of the serialized payload. This vulnerability is fixed in 5.12.1.

Timeline

Published 2026-05-27

Modified 2026-06-02

External references

NVD MITRE Exploit-DB Sploitus VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-44660

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Ultrajson Project Ultrajson"

All exposed Ultrajson Project Ultrajson instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Ultrajson"

HTTP body or banner mentions "Ultrajson" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-44660