CVEvulnerability

CVE-2026-54911

6.5 MEDIUM Published 2026-06-22 Modified 2026-06-26 Official page ↗
Status
Analyzed
Published
2026-06-22
Last modified
2026-06-26
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.5 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weaknesses
CWE-20

Description

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.

Affected configurations

• ultrajson project ultrajson (< 5.13.0)

Related

Weakness · CWE (1)

  • CWE-20 Improper Input Validation weakness

References