Critical 9.8Published Jan 18, 2021

CVE-2021-3177Python 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 untru…

Updated under an hour ago (Oct 27, 2026, 2:00 AM ET)

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It affects Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP and 12 other products. Add what you run to find out whether that includes you.

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Every CVE for Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP

Exploited in the last 30 days

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: 9.8 CRITICAL (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-120
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: mitre
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 14, 2026

Affected products

Affected products

Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
python python python: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	NVD
fedoraproject fedora fedoraproject:fedora	32; 33	NVD
netapp active_iq_unified_manager netapp:active_iq_unified_manager	all versions; all versions	NVD
netapp ontap_select_deploy_administration_utility netapp:ontap_select_deploy_administration_utility	all versions	NVD
debian debian_linux debian:debian_linux	9.0	NVD
oracle communications_cloud_native_core_network_function_cloud_native_environment oracle:communications_cloud_native_core_network_function_cloud_native_environment	22.2.0	NVD
oracle communications_offline_mediation_controller oracle:communications_offline_mediation_controller	12.0.0.3.0	NVD
1–10 of 13

References

References

https://bugs.python.org/issue42938	exploit, issue-tracking, patch, vendor-advisory
https://github.com/python/cpython/pull/24239	patch, third-party-advisory
https://python-security.readthedocs.io/vuln/ctypes-buffer-overflow-pycarg_repr.html	patch, third-party-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MGSV6BJQLRQ6RKVUXK7JGU7TP4QFGQXC/	vendor-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NQPARTLNSFQVMMQHPNBFOCOZOO3TMQNA/	vendor-advisory
https://security.gentoo.org/glsa/202101-18	vendor-advisory, third-party-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7GZV74KM72O2PEJN2C4XP3V5Q5MZUOO/	vendor-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CCFZMVRQUKCBQIG5F2CBVADK63NFSE4A/	vendor-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BRHOCQYX3QLDGDQGTWQAUUT2GGIZCZUO/	vendor-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NXSMBHES3ANXXS2RSO5G6Q24BR4B2PWK/	vendor-advisory
1–10 of 27

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.