Excessive read buffering DoS in http.client

The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through repeated unterminated markup declarations when processing uncontrolled data.

Configuration Injection via Carriage Return (\r) in write() method

Accessibility. A logging issue was addressed with improved data redaction.

An issue was discovered in Python before 3.8.18, 3.9.x before 3.9.18, 3.10.x before 3.10.13, and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created, receives data into the socket buffer, and then is closed quickly, there is a brief window where the SSLSocket instance will detect the socket as "not connected" and won't initiate a handshake, but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication, and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.)

A vulnerability was discovered in Python. A quadratic algorithm exists when processing inputs to the IDNA (RFC 3490) decoder, such that a crafted unreasonably long name being presented to the decoder could lead to a CPU denial of service. Hostnames are often supplied by remote servers that could be controlled by a malicious actor, which could trigger excessive CPU consumption on the client attempting to make use of an attacker-supplied hostname.

A flaw was found in the Python tarfile module. Extracting a crafted TAR archive with the tarfile.extract or tarfile.extractall functions could lead to a directory traversal vulnerability, resulting in overwrite of arbitrary files.

An issue was discovered in Python 3.11 through 3.11.4. If a path containing '\0' bytes is passed to os.path.normpath(), the path will be truncated unexpectedly at the first '\0' byte. There are plausible cases in which an application would have rejected a filename for security reasons in Python 3.10.x or earlier, but that filename is no longer rejected in Python 3.11.x.

Last updated 19 September 2024

Last updated 7 May 2025

An issue in the urllib.parse component of Python before 3.11.4 allows attackers to bypass blocklisting methods by supplying a URL that starts with blank characters.

A vulnerability has been found in the CPython venv module and CLI where path names provided when creating a virtual environment were not quoted properly, allowing the creator to inject commands into virtual environment "activation" scripts (ie "source venv/bin/activate"). This means that attacker-controlled virtual environments are able to run commands when the virtual environment is activated. Virtual environments which are not created by an attacker or which aren't activated before being used (ie "./venv/bin/python") are not affected.