SB2026061747 - Input validation error in ultrajson

Description

This security bulletin contains information about 1 vulnerability.

1) Input validation error (CVE-ID: CVE-2026-54911)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to bypass input validation and alter serialized data integrity.

The vulnerability exists due to improper input validation in ujson.dumps(), ujson.dump(), and ujson.encode() when processing malformed or truncated UTF-8 byte sequences with reject_bytes=False. A remote attacker can supply crafted byte sequences to bypass input validation and alter serialized data integrity.

The issue occurs only when the reject_bytes=False option is used.

Remediation

Install update from vendor's website.

References

• https://github.com/ultrajson/ultrajson/security/advisories/GHSA-3j69-69wj-xqx2
• https://github.com/ultrajson/ultrajson/commit/169eaf36b1116fece5034ee79a7a0ef3f6deedcf