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CVE-2021-3177

Published: Jan 19, 2021Updated: Dec 18, 2025 Sources: CVE List NVD BDU csafCWE-120
NVD MITRE
9.8CVSSCRITICAL
EPSS Score
23.3%
Top 2.5%
CISA KEV
Not in KEV
Exploits
1 Known
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-120

Affected Products

n/an/a
UbuntuCanonical Ltd.
On-premOS
Operating Systems / linux-distro
Astra Linux Special EditionООО «РусБИТех-Астра»
On-premOS
Operating Systems / linux-distro
SUSE Linux Enterprise Server for SAP ApplicationsNovell Inc.
On-premOS
Operating Systems / linux-distro
SUSE OpenStack CloudNovell Inc.
On-prem
Operating Systems / linux-distro
canonical ltd.commercialGBOperating Systemsaka canonical
ооо «русбитех-астра»commercialRUOperating Systemsaka rusbitech-astra
novell inc.commercialUSOperating Systems
and 34 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

1 exploit source identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
Privilege Escalation
View detailed technique mapping

References

https://bugs.python.org/issue42938
bugs.python.org
https://github.com/python/cpython/pull/24239
github.com
https://python-security.readthedocs.io/vuln/ctypes-buffer-overflow-pycarg_repr.html
python-security.readthedocs.io
and 74 more references View all →

Timeline

Published
Jan 19, 2021
Last Updated
Dec 18, 2025

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