CVE-2021-3177
CriticalCVSS 9.8Exploitation Probability (EPSS)
Very high risk98th percentile - higher than 98% of all known CVEs
Summary
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.
Risk Assessment
An attacker could remotely execute code in an application using the vulnerable Python version, potentially leading to system compromise or data breach.
Recommendation
Upgrade Python to version 3.9.2 or later, which includes a fix for this vulnerability.
Other vulnerabilities in Python
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- CVE-2022-42919High
A vulnerability in Python 3.9.x before 3.9.16 and 3.10.x before 3.10.9 on Linux allows local privilege escalation in a non-default configuration. The multiprocessing library with the forkserver start method permits pickle deserialization from any user on the same local network of the machine.
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A vulnerability in the urllib.parse component of Python before version 3.11.4 allows attackers to bypass blocklisting methods by supplying a URL that starts with blank characters.
- CVE-2020-10735High
A flaw was found in Python. In algorithms with quadratic time complexity using non-binary bases, when using int("text"), a system could take 50ms to parse an int string with 100,000 digits and 5s for 1,000,000 digits (float, decimal, int.from_bytes(), and int() for binary bases 2, 4, 8, 16, and 32 are not affected). The highest threat from this vulnerability is to system availability.
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A flaw in Python's HTTP client code, when improperly handling an HTTP response, may cause the client script to enter an infinite loop, consuming CPU time. The highest threat is to system availability.
- CVE-2022-0391High
A flaw in Python's urllib.parse module, where the urlparse method does not sanitize input and allows characters like '\r' and '\n' in the URL path, enabling an attacker to craft a URL that leads to injection attacks. Affected versions are earlier than 3.10.0b1, 3.9.5, 3.8.11, 3.7.11, and 3.6.14.
- CVE-2021-29921Critical
In Python before 3.9.5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.
- CVE-2021-23336Medium
The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and urllib.parse.parse_qs by using a vector called parameter cloaking. When the attacker can separate query parameters using a semicolon (;), they can cause a difference in the interpretation of the request between the proxy (running with default configuration) and the server.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

