Incorrect Authorization Affecting ujson package, versions [,5.13.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-UJSON-17391481
- published21 Jun 2026
- disclosed19 Jun 2026
- creditErdembileg Ariunbold
Introduced: 19 Jun 2026
NewCVE-2026-54911 (opens in a new tab)How to fix?
Upgrade ujson to version 5.13.0 or higher.
Overview
ujson is an Ultra fast JSON encoder and decoder for Python
Affected versions of this package are vulnerable to Incorrect Authorization in the ujson.dumps function when the reject_bytes parameter is set to False. An attacker can cause data integrity issues or bypass input validation by submitting malformed or truncated UTF-8 byte sequences, which are silently rewritten into different Unicode characters instead of being rejected.
Workaround
This vulnerability can be mitigated by decoding bytes to strings in Python before passing them to ujson.dumps().