CVE-2026-44660
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductUltrajson
PublishedMay 27, 2026
First seenMay 27, 2026
Weakness typeCWE-401CWE-401
How to fix
Update
- ultrajson_project ultrajson5.12.1 or later
- ujson5.12.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| ultrajson_project ultrajson | v < 5.12.1 | 5.12.1 |
| ujsonPyPI | v < 5.12.1 | 5.12.1 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
In the Intelligence 360 plan
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.