PSF-2023-2 Parsing errors in email/_parseaddr.py lead to incorrect value in email address part of tuple

The email module of Python through 3.11.3 incorrectly parses e-mail addresses that contain a special character. The wrong portion of an RFC2822 header is identified as the value of the addr-spec. In some applications, an attacker can bypass a protection mechanism in which application access is...

PSF-2022-11 Buffer overflow in the _sha3 module in Python 3.10 and older

The Keccak XKCP SHA-3 reference implementation before fdc6fef has an integer overflow and resultant buffer overflow that allows attackers to execute arbitrary code or eliminate expected cryptographic properties. This occurs in the sponge function interface...

PSF-2019-11 HTTP Header Injection (follow-up of CVE-2016-5699)

An issue was discovered in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.3. CRLF injection is possible if the attacker controls a url parameter, as demonstrated by the first argument to urllib.request.urlopen with \r\n specifically in the path component of a URL that...

PSF-2023-7 Reference count issue in _asyncio._swap_current_task()

An issue in Python CPython 3.12.0b1 allows an attacker to obtain sensitive information via the asyncio.swapcurrenttask component...

PSF-2022-9 Linux specific local privilege escalation via the multiprocessing forkserver start method

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 Python multiprocessing library, when used with the forkserver start method on Linux, allows pickles to be deserialized from any user in the same machine local network...

PSF-2019-12 urllib module local_file:// scheme

urllib in Python 2.x through 2.7.16 supports the localfile: scheme, which makes it easier for remote attackers to bypass protection mechanisms that blacklist file: URIs, as demonstrated by triggering a urllib.urlopen'localfile:///etc/passwd' call...

PSF-2021-2 ipaddress leading zeros in IPv4 address

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...

PSF-2020-5 http.client: HTTP Header Injection in the HTTP method

http.client in Python 3.x before 3.5.10, 3.6.x before 3.6.12, 3.7.x before 3.7.9, and 3.8.x before 3.8.5 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of HTTPConnection.request...

PSF-2018-6 pickle.load denial of service

Modules/pickle.c in Python before 3.7.1 has an integer overflow via a large LONGBINPUT value that is mishandled during a "resize to twice the size" attempt. This issue might cause memory exhaustion, but is only relevant if the pickle format is used for serializing tens or hundreds of gigabytes of...

PSF-2019-10 HTTP Header Injection (follow-up of CVE-2016-5699)

An issue was discovered in urllib2 in Python 2.x through 2.7.16 and urllib in Python 3.x through 3.7.3. CRLF injection is possible if the attacker controls a url parameter, as demonstrated by the first argument to urllib.request.urlopen with \r\n specifically in the query string after a ? charact...

PSF-2022-7 CVE-2021-3737: urllib HTTP client possible infinite loop on a 100 Continue response

A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client script enter an infinite loop, consuming CPU time. The highest threat from this vulnerability is to system availability...

PSF-2019-8 TALOS-2018-0758 SSL CRL distribution points Denial of Service

An exploitable denial-of-service vulnerability exists in the X509 certificate parser of Python.org Python 2.7.11 / 3.6.6. A specially crafted X509 certificate can cause a NULL pointer dereference, resulting in a denial of service. An attacker can initiate or accept TLS connections using crafted...

PSF-2019-3 urlsplit does not handle NFKC normalization (second fix)

A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3 affecting versions 2.7, 3.5, 3.6, 3.7 and from v3.8.0a4 through v3.8.0b1, which still allows an attacker to exploit CVE-2019-9636 by abusing the user and password parts of a URL...

PSF-2020-4 Py_SetPath(): _Py_CheckPython3 uses uninitialized DLL path

In Python 3.6 through 3.6.10, 3.7 through 3.7.8, 3.8 through 3.8.4rc1, and 3.9 through 3.9.0b4 on Windows, a Trojan horse python3.dll might be used in cases where CPython is embedded in a native application. This occurs because python3X.dll may use an invalid search path for python3.dll loading...

PSF-2020-2 Infinite loop in tarfile module while opening a crafted file

In Lib/tarfile.py in Python through 3.8.3, an attacker is able to craft a TAR archive leading to an infinite loop when opened by tarfile.open, because procpax lacks header validation...

PSF-2017-7 Expat 2.2.1

XML External Entity vulnerability in libexpat 2.2.0 and earlier Expat XML Parser Library allows attackers to put the parser in an infinite loop using a malformed external entity definition from an external DTD...

PSF-2017-6 PyString_DecodeEscape integer overflow

CPython aka Python up to 2.7.13 is vulnerable to an integer overflow in the PyStringDecodeEscape function in stringobject.c, resulting in heap-based buffer overflow and possible arbitrary code execution...

PSF-2023-6 hmac.compare_digest() accumulator not constant-time

An issue was discovered in comparedigest in Lib/hmac.py in Python through 3.9.1. Constant-time-defeating optimisations were possible in the accumulator variable in hmac.comparedigest...

PSF-2020-3 [CVE-2020-14422] Hash collisions in IPv4Interface and IPv6Interface

Lib/ipaddress.py in Python through 3.8.3 improperly computes hash values in the IPv4Interface and IPv6Interface classes, which might allow a remote attacker to cause a denial of service if an application is affected by the performance of a dictionary containing IPv4Interface or IPv6Interface...

PSF-2018-1 Expat 2.2.1

An integer overflow during the parsing of XML using the Expat library. This vulnerability affects Firefox 50...

PSF-2019-7 CVE-2019-18348: CRLF injection via the host part of the url passed to urlopen()

An issue was discovered in urllib2 in Python 2.x through 2.7.17 and urllib in Python 3.x through 3.8.0. CRLF injection is possible if the attacker controls a url parameter, as demonstrated by the first argument to urllib.request.urlopen with \r\n specifically in the host component of a URL follow...

PSF-2019-5 email.utils.parseaddr mistakenly parse an email

An issue was discovered in Python through 2.7.16, 3.x through 3.5.7, 3.6.x through 3.6.9, and 3.7.x through 3.7.4. The email module wrongly parses email addresses that contain multiple @ characters. An application that uses the email module and implements some kind of checks on the From/To header...

PSF-2022-6 CVE-2021-3733: ReDoS in urllib.request

There's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client such as web browser connects to, could trigger a Regular Expression Denial of Service ReDOS during an authentication request with a specially crafted payload that is sen...

PSF-2021-4 Information disclosure via pydoc getfile

There's a flaw in Python 3's pydoc. A local or adjacent attacker who discovers or is able to convince another local or adjacent user to start a pydoc server could access the server and use it to disclose sensitive information belonging to the other user that they would not normally be able to...

PSF-2026-27

bz2.BZ2Decompressor objects could be reused after a decompression error. If an application caught the resulting OSError and retried with the same decompressor, crafted input could cause the decompressor to resume from an invalid internal state and perform out-of-bounds writes to a stack buffer...

PSF-2019-6 Reflected XSS in DocXMLRPCServer

The documentation XML-RPC server in Python through 2.7.16, 3.x through 3.6.9, and 3.7.x through 3.7.4 has XSS via the servertitle field. This occurs in Lib/DocXMLRPCServer.py in Python 2.x, and in Lib/xmlrpc/server.py in Python 3.x. If setservertitle is called with untrusted input, arbitrary...

PSF-2017-1 JSONDecoder.raw_decode

Array index error in the scanstring function in the json module in Python 2.7 through 3.5 and simplejson before 2.6.1 allows context-dependent attackers to read arbitrary process memory via a negative index value in the idx argument to the rawdecode function...

PSF-2022-5 http.server: Open Redirection if the URL path starts with //

Python 3.x through 3.10 has an open redirection vulnerability in lib/http/server.py due to no protection against multiple / at the beginning of URI path which may leads to information disclosure. NOTE: this is disputed by a third party because the http.server.html documentation page states...

PSF-2022-3 Windows: vulnerable zlib 1.2.11

zlib before 1.2.12 allows memory corruption when deflating i.e., when compressing if the input has many distant matches...

PSF-2020-6 CJK codecs tests call eval() on content retrieved via HTTP

In Python 3 through 3.9.0, the Lib/test/multibytecodecsupport.py CJK codec tests call eval on content retrieved via HTTP...

PSF-2019-1 smtplib unlimited read

The smtplib module doesn't limit the amount of read data in its call to readline. An erroneous or malicious SMTP server can trick the smtplib module to consume large amounts of memory...

PSF-2019-2 HTTPoxy attack

The CGIHandler class in Python before 2.7.12 does not protect against the HTTPPROXY variable name clash in a CGI script, which could allow a remote attacker to redirect HTTP requests...

PSF-2026-21

http.cookies.Morsel.jsoutput returns an inline snippet and only escapes " for JavaScript string context. It does not neutralize the HTML parser-sensitive sequence inside the generated script element. Mitigation base64-encodes the cookie value to disallow escaping using cookie value...

PSF-2017-4 Zlib 1.2.11

The inflateMark function in inflate.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving left shifts of negative integers...

PSF-2023-9 os.path.normpath() truncates on null bytes

Passing a path with null bytes to the os.path.normpath function causes the returned path to be unexpectedly truncated at the first occurrence of null bytes within the path. Python versions before 3.11.0 didn’t truncate the path on null bytes. If allowlisting is applied before a call to...

PSF-2024-6

CPython 3.9 and earlier doesn't disallow configuring an empty list "" for SSLContext.setnpnprotocols which is an invalid value for the underlying OpenSSL API. This results in a buffer over-read when NPN is used see CVE-2024-5535 for OpenSSL. This vulnerability is of low severity due to NPN being...

PSF-2018-2 Python 2.7 readahead is not thread safe

Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it appears that Python 2.7.17 and prior may also be vulnerable however this has not been confirmed. The vulnerability lies when multiply threads are...

PSF-2023-11 Use-after-free in heappushpop() of heapq module

A use-after-free exists in Python through 3.9 via heappushpop in heapq...

PSF-2022-10 Slow IDNA decoding with large strings

An issue was discovered in Python before 3.11.1. An unnecessary quadratic algorithm exists in one path when processing some 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...

PSF-2019-14 Regular Expression Denial of Service in http.cookiejar

The regex http.cookiejar.LOOSEHTTPDATERE is vulnerable to regular expression denial of service "REDoS". LOOSEHTTPDATERE.match is called when using http.cookiejar.CookieJar to parse Set-Cookie headers returned by a HTTP server. Processing a response from a malicious HTTP server can lead to extreme...

PSF-2019-9 urlsplit does not handle NFKC normalization

Python 2.7.x through 2.7.16 and 3.x through 3.7.2 is affected by: Improper Handling of Unicode Encoding with an incorrect netloc during NFKC normalization. The impact is: Information disclosure credentials, cookies, etc. that are cached against a given hostname. The components are:...

PSF-2023-10 DoS when reading malformed Apple Property List files in binary format

readints in plistlib.py in Python through 3.9.1 is vulnerable to a potential DoS attack via CPU and RAM exhaustion when processing malformed Apple Property List files in binary format...

PSF-2021-3 ctypes: Buffer overflow in PyCArg_repr

Python 3.x through 3.9.1 has a buffer overflow in PyCArgrepr 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 cdouble.fromparam. This occurs because sprintf is...

PSF-2024-1

An issue was found in the CPython tempfile.TemporaryDirectory class affecting versions 3.12.1, 3.11.7, 3.10.13, 3.9.18, and 3.8.18 and prior. The tempfile.TemporaryDirectory class would dereference symlinks during cleanup of permissions-related errors. This means users which can run privileged...

PSF-2023-5 XML External Entity issue in plistlib module

An XML External Entity XXE issue was discovered in Python through 3.9.1. The plistlib module no longer accepts entity declarations in XML plist files to avoid XML vulnerabilities...

PSF-2023-8 Bypass TLS handshake on closed sockets

Instances of ssl.SSLSocket are vulnerable to a bypass of the TLS handshake and included protections like certificate verification and treating sent unencrypted data as if it were post-handshake TLS encrypted data. The vulnerability is caused when a socket is connected, data is sent by the malicio...

PSF-2022-4 Prevent DoS by large str-int conversions

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.frombytes, and int for binary bases 2, 4, 8, 16, and 32 are no...

PSF-2022-1 mailcap shell command injection

In Python aka CPython up to 3.10.8, the mailcap module does not add escape characters into commands discovered in the system mailcap file. This may allow attackers to inject shell commands into applications that call mailcap.findmatch with untrusted input if they lack validation of user-provided...

PSF-2026-24

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 getpeername0, ftpcp still calls parse227 directly and passes the raw attacker-controllable IP address and port t...

PSF-2020-8 urllib basic auth regex denial of service

Python 2.7 through 2.7.17, 3.5 through 3.5.9, 3.6 through 3.6.10, 3.7 through 3.7.6, and 3.8 through 3.8.1 allows an HTTP server to conduct Regular Expression Denial of Service ReDoS attacks against a client because of urllib.request.AbstractBasicAuthHandler catastrophic backtracking...