ujson: UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+
CVE-2026-54911 is fixed in ujson on 1 platform by DEBIAN-CVE-2026-54911 (version 5.13.0-1), released July 9, 2026. It is not reported as exploited. Patch Radar priority: Routine.
UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.13.0, ujson.dumps() (or ujson.dump() or ujson.encode()) have a reject_bytes=False option. When set, they may accept malformed or truncated UTF-8 byte sequences, silently rewriting them into different Unicode characters instead of rejecting them. This leads to input validation bypass and data integrity issues. This vulnerability is fixed in 5.13.0.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| ujson · Debian 14 | 5.13.0-1 | DEBIAN-CVE-2026-54911 | Jul 9, 2026 |
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