Back to overview

CVE-2026-54911

MEDIUM
6.5
CVSS 3.1
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.

Metadata

CVE ID
CVE-2026-54911
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-06-16 13:49 UTC
Published
2026-06-22 20:53 UTC
Last updated
2026-06-22 20:53 UTC
Primary CWE
CWE-20
CWE-20: Improper Input Validation
Vendor / Product
ultrajson / ultrajson
Sources
cve.org  ·  NVD

Severity & Metrics

6.5 MEDIUM CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Affected products (1)
VendorProductPlatformVersions
ultrajson ultrajson — < 5.13.0
Weakness (CWE)
CWESourceDescription
CWE-20 cna CWE-20: Improper Input Validation
CVSS scores (1)
ScoreSeverityVersionSourceVector
6.5 MEDIUM 3.1 cna CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
References (3)
Back to overview