CVE-2026-54911 | BDVDB-2026-342144 Detail

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.

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Exploit#

History#

1. Version 12026-06-22Record published in the CVE List.
2. Version 22026-06-23Most recent update recorded in the CVE List.