Threats affecting pkg:github/python/cpython

The ftpcp() function in Lib/ftplib.py was not updated when CVE-2021-4189 was fixed. While makepasv() was patched to replace server-supplied PASV host addresses with the actual peer address (getpeername()[0]), ftpcp() still calls parse227() directly and passes the raw attacker-controllable IP address and port to target.sendport(). This patch is related to CVE-2021-4189.

When an Expat parser with a registered ElementDeclHandler parses an inline document type definition containing a deeply nested content model a C stack overflow occurs.

The import hook in CPython that handles legacy *.pyc files (SourcelessFileLoader) is incorrectly handled in FileLoader (a base class) and so does not use io.open_code() to read the .pyc files. sys.audit handlers for this audit event therefore do not fire.

The email module, specifically the "BytesGenerator" class, didn’t properly quote newlines for email headers when serializing an email message allowing for header injection when an email is serialized. This is only applicable if using "LiteralHeader" writing headers that don't respect email folding rules, the new behavior will reject the incorrectly folded headers in "BytesGenerator".

User-controlled header names and values containing newlines can allow injecting HTTP headers.

When building nested elements using xml.dom.minidom methods such as appendChild() that have a dependency on _clear_id_cache() the algorithm is quadratic. Availability can be impacted when building excessively nested documents.

When loading a plist file, the plistlib module reads data in size specified by the file itself, meaning a malicious file can cause OOM and DoS issues

CVE-2025-13836 is a medium severity vulnerability in the Python Software Foundation's CPython implementation. When reading HTTP responses without specifying a read amount, the client defaults to using the Content-Length header. A malicious server can exploit this behavior to cause the client to read excessive data into memory, potentially leading to out-of-memory (OOM) conditions or denial of service (DoS). This affects multiple CPython versions from 0 through 3.15.0a1. There are no known exploits in the wild and no patch or official remediation information is currently available.

CVE-2025-8194 is a high severity vulnerability in the Python Software Foundation's CPython implementation affecting the tarfile module. The flaw causes the TarFile extraction and entry enumeration APIs to enter an infinite loop when processing tar archives with negative offsets. This results in deadlock during parsing of maliciously crafted tar files. The vulnerability affects specific CPython versions including 3.10.0 through 3.14.0a1. No official patch is listed, but a mitigation patch is available as a third-party workaround.

CVE-2025-4138 is a path traversal vulnerability in the Python tarfile module that allows the extraction filter to be bypassed, enabling symlink targets to point outside the intended extraction directory and permitting modification of some file metadata. This affects usage of TarFile.extractall() or TarFile.extract() when using the filter parameter set to "data" or "tar". The default filter value changed to "data" starting with Python 3.14, so code relying on this default is also affected. This vulnerability does not significantly impact source distribution installations, which already allow arbitrary code execution during build.

There is a LOW severity vulnerability affecting CPython, specifically the 'http.cookies' standard library module. When parsing cookies that contained backslashes for quoted characters in the cookie value, the parser would use an algorithm with quadratic complexity, resulting in excess CPU resources being used while parsing the value.