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.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-2619-1 python3.5 security update
Debian DLA Debian DLA DLA-2919-1 python2.7 security update
Debian DLA Debian DLA DLA-3432-1 python2.7 security update
EUVD EUVD EUVD-2021-26520 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.
Ubuntu USN Ubuntu USN USN-4754-1 Python vulnerabilities
Ubuntu USN Ubuntu USN USN-4754-3 Python vulnerabilities
Ubuntu USN Ubuntu USN USN-4754-4 Python 2.7 vulnerability
Ubuntu USN Ubuntu USN USN-4754-5 Python vulnerability
Ubuntu USN Ubuntu USN USN-6891-1 Python vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

References
Link Providers
https://bugs.python.org/issue42938 cve-icon cve-icon
https://github.com/python/cpython/pull/24239 cve-icon cve-icon
https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2021/04/msg00005.html cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2022/02/msg00013.html cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BRHOCQYX3QLDGDQGTWQAUUT2GGIZCZUO/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCFZMVRQUKCBQIG5F2CBVADK63NFSE4A/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FPE7SMXYUIWPOIZV4DQYXODRXMFX3C5E/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MGSV6BJQLRQ6RKVUXK7JGU7TP4QFGQXC/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MP572OLHMS7MZO4KUPSCIMSZIA5IZZ62/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NODWHDIFBQE5RU5PUWUVE47JOT5VCMJ2/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NQPARTLNSFQVMMQHPNBFOCOZOO3TMQNA/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NXSMBHES3ANXXS2RSO5G6Q24BR4B2PWK/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/V6XJAULOS5JVB2L67NCKKMJ5NTKZJBSD/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y4KSYYWMGAKOA2JVCQA422OINT6CKQ7O/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YDTZVGSXQ7HR7OCGSUHTRNTMBG43OMKU/ cve-icon cve-icon
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7GZV74KM72O2PEJN2C4XP3V5Q5MZUOO/ cve-icon cve-icon
https://news.ycombinator.com/item?id=26185005 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2021-3177 cve-icon
https://python-security.readthedocs.io/vuln/ctypes-buffer-overflow-pycarg_repr.html cve-icon cve-icon
https://security.gentoo.org/glsa/202101-18 cve-icon cve-icon
https://security.netapp.com/advisory/ntap-20210226-0003/ cve-icon cve-icon
https://www.cve.org/CVERecord?id=CVE-2021-3177 cve-icon
https://www.oracle.com//security-alerts/cpujul2021.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpujan2022.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpujul2022.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpuoct2021.html cve-icon cve-icon
History

Thu, 18 Dec 2025 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2025-12-18T15:03:34.545Z

Reserved: 2021-01-19T00:00:00.000Z

Link: CVE-2021-3177

cve-icon Vulnrichment

Updated: 2024-08-03T16:45:51.394Z

cve-icon NVD

Status : Modified

Published: 2021-01-19T06:15:12.967

Modified: 2025-12-18T15:15:48.873

Link: CVE-2021-3177

cve-icon Redhat

Severity : Moderate

Publid Date: 2021-01-19T00:00:00Z

Links: CVE-2021-3177 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses