high7.5
CVE-2026-44660
UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+.
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | ujson | <= 5.12.0 | 5.12.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Ultrajson Project | Ultrajson | before 5.12.1 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-c38f-wx89-p2xg
- https://github.com/ultrajson/ultrajson/security/advisories/GHSA-c38f-wx89-p2xg
- https://github.com/ultrajson/ultrajson/commit/82af1d0ac01d09aa40c887b460d44b9d9f4bccd9
- https://github.com/ultrajson/ultrajson/releases/tag/5.12.1
- https://nvd.nist.gov/vuln/detail/CVE-2026-44660