When using http.cookies.Morsel, user-controlled cookie values and parameters can allow injecting HTTP headers into messages. Patch rejects all control characters within cookie names, values, and parameters.
POP3 command injection in user-controlled commands
The poplib module, when passed a user-controlled command, can have
additional commands injected using newlines. Mitigation rejects commands
containing control characters.
IMAP command injection in user-controlled commands
The imaplib module, when passed a user-controlled command, can have additional commands injected using newlines. Mitigation rejects commands containing control characters.
Folding email comments of unfoldable characters doesn't preserve parenthesis
When folding a long comment in an email header containing exclusively unfoldable characters, the parenthesis would not be preserved. This could be used for injecting headers into email messages where addresses are user-controlled and not sanitized.
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 reading an HTTP response from a server, if no read amount is specified, the default behavior will be to use Content-Length. This allows a malicious server to cause the client to read large amounts of data into memory, potentially causing OOM or other DoS.
ZIP64 End of Central Directory (EOCD) Locator record offset not checked
The 'zipfile' module would not check the validity of the ZIP64 End of
Central Directory (EOCD) Locator record offset value would not be used to
locate the ZIP64 EOCD record, instead the ZIP64 EOCD record would be
assumed to be the previous record in the ZIP archive. This could be abused
to create ZIP archives that are handled differently by the 'zipfile' module
compared to other ZIP implementations.
Remediation maintains this behavior, but checks that the offset specified
in the ZIP64 EOCD Locator record matches the expected value.
Tarfile infinite loop during parsing with negative member offset
There is a defect in the CPython “tarfile” module affecting the “TarFile” extraction and entry enumeration APIs. The tar implementation would process tar archives with negative offsets without error, resulting in an infinite loop and deadlock during the parsing of maliciously crafted tar archives.
This vulnerability can be mitigated by including the following patch after importing the “tarfile” module: https://gist.github.com/sethmlarson/1716ac5b82b73dbcbf23ad2eff8b33e1
HTMLParser quadratic complexity when processing malformed inputs
The html.parser.HTMLParser class had worse-case quadratic complexity when processing certain crafted malformed inputs potentially leading to amplified denial-of-service.
Use-after-free in "unicode_escape" decoder with error handler
There is an issue in CPython when using `bytes.decode("unicode_escape", error="ignore|replace")`. If you are not using the "unicode_escape" encoding or an error handler your usage is not affected. To work-around this issue you may stop using the error= handler and instead wrap the bytes.decode() call in a try-except catching the DecodeError.
Mishandling of comma during folding and unicode-encoding of email headers
During an address list folding when a separating comma ends up on a folded line and that line is to be unicode-encoded then the separator itself is also unicode-encoded. Expected behavior is that the separating comma remains a plan comma. This can result in the address header being misinterpreted by some mail servers.
URL parser allowed square brackets in domain names
The Python standard library functions `urllib.parse.urlsplit` and `urlparse` accepted domain names that included square brackets which isn't valid according to RFC 3986. Square brackets are only meant to be used as delimiters for specifying IPv6 and IPvFuture hosts in URLs. This could result in differential parsing across the Python URL parser and other specification-compliant URL parsers.
Improper validation of IPv6 and IPvFuture addresses
The urllib.parse.urlsplit() and urlparse() functions improperly validated bracketed hosts (`[]`), allowing hosts that weren't IPv6 or IPvFuture. This behavior was not conformant to RFC 3986 and potentially enabled SSRF if a URL is processed by more than one URL parser.
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.
Regular-expression DoS when parsing TarFile headers
There is a MEDIUM severity vulnerability affecting CPython.
Regular expressions that allowed excessive backtracking during tarfile.TarFile header parsing are vulnerable to ReDoS via specifically-crafted tar archives.
Infinite loop when iterating over zip archive entry names from zipfile.Path
There is a HIGH severity vulnerability affecting the CPython "zipfile"
module affecting "zipfile.Path". Note that the more common API "zipfile.ZipFile" class is unaffected.
When iterating over names of entries in a zip archive (for example, methods
of "zipfile.Path" like "namelist()", "iterdir()", etc)
the process can be put into an infinite loop with a maliciously crafted
zip archive. This defect applies when reading only metadata or extracting
the contents of the zip archive. Programs that are not handling
user-controlled zip archives are not affected.