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CVE-2026-54911

UltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps() PUBLISHED

Description (CNA)

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 (CNA)

Vendor / productVersions
ultrajson / ultrajsonaffected < 5.13.0

CWE

CWE-20

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.