{"cve":"CVE-2026-44660","nvd":{"published":"2026-05-27T21:16:17.650","modified":"2026-06-17T10:51:12.350","status":"Analyzed","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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","score":8.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-401"],"references":["https://github.com/ultrajson/ultrajson/commit/82af1d0ac01d09aa40c887b460d44b9d9f4bccd9","https://github.com/ultrajson/ultrajson/releases/tag/5.12.1","https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg","https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg"],"products":["ultrajson_project:ultrajson"],"source":"nvd","synced_at":"2026-10-19T22:36:28.938604137+00:00"},"epss":{"cve":"CVE-2026-44660","score":0.00421,"percentile":0.36439,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-c38f-wx89-p2xg","url":"https://osv.dev/vulnerability/GHSA-c38f-wx89-p2xg","summary":"UltraJSON has a Memory Leak in ujson.dump() on Write Failure","modified":"2026-09-10T03:51:05.194201525Z","packages":[{"ecosystem":"PyPI","name":"ujson","purl":"pkg:pypi/ujson","ranges":["<5.12.1"],"fixed":["5.12.1"]}]},{"id":"PYSEC-2026-2293","url":"https://osv.dev/vulnerability/PYSEC-2026-2293","summary":"","modified":"2026-07-13T07:15:45.423783162Z","packages":[{"ecosystem":"PyPI","name":"ujson","purl":"pkg:pypi/ujson","ranges":["<5.12.1"],"fixed":["5.12.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}