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CriticalPython

CVE-2021-3177

Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Python applications that accept floating-point numbers as untrusted input, as demonstrated by a 1e300 argument to c_double.from_param. This occurs because sprintf is used unsafely.

CVSS Base Score
9.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Probability
98%EPSS PERCENTILE0100

More exploitable than 98% of all CVEs · Top 2%

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Details
Published
2021-01-19
Last modified
2026-10-14
Affected
Python
References
NVD Detail OSV.dev GitHub Advisories

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Data from the National Vulnerability Database (NVD), CISA KEV, and FIRST.org EPSS. This product uses the NVD API but is not endorsed or certified by the NVD. EPSS is a probability estimate, not a guarantee of exploitation.