What’s Vulnerable › Vulnerabilities

CVE-2021-3177

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 24.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-01-19 · updated 2026-10-14
• Weakness: CWE-120

Description

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.

Affected products

• Debian Linux: 9.0
• Fedoraproject Fedora: 32, 33
• Active IQ Unified Manager for VMware vSphere, Linux, and Microsoft Windows: all versions
• NetApp ONTAP Select Deploy administration utility: all versions
• Oracle Communications Cloud Native Core Network Function Cloud Native Environment: 22.2.0
• Oracle Communications Offline Mediation Controller: 12.0.0.3.0
• Oracle Corporation Communications Pricing Design Center: 12.0.0.3.0
• Oracle Corporation Enterprise Manager Ops Center: 12.4.0.0
• Oracle Corporation Oracle ZFS Storage Appliance Kit: 8.8
• Python: from 3.6.0 through 3.6.12; from 3.7.0 through 3.7.9; from 3.8.0 through 3.8.7; from 3.9.0 through 3.9.1

References

• https://bugs.python.org/issue42938
• https://github.com/python/cpython/pull/24239
• https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
• https://lists.debian.org/debian-lts-announce/2021/04/msg00005.html
• https://lists.debian.org/debian-lts-announce/2022/02/msg00013.html
• https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BRHOCQYX3QLDGDQGTWQAUUT2GGIZCZUO/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCFZMVRQUKCBQIG5F2CBVADK63NFSE4A/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FPE7SMXYUIWPOIZV4DQYXODRXMFX3C5E/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MGSV6BJQLRQ6RKVUXK7JGU7TP4QFGQXC/

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