A remote, unauthenticated TLS client can make a server crash or call through a freed pointer if its snicallback assigns a different context to SSLSocket.context (the documented way to select a certificate per server name) and nothing else keeps the original ssl.SSLContext alive. Typical cases are servers that create an SSLContext per connection or replace it while connections are open; servers that wrap their listening socket with it are not affected.

Mitigation: keep a reference to every SSLContext that sets snicallback for the lifetime of the server. TLS clients are not affected.

Last updated 6 July 2026

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.

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.

In CPython 3.13 and earlier, the tarfile module's data and tar extraction filters are vulnerable to crafted archives containing a hard link to a symbolic link. Such archives may cause extraction to modify the permissions or modification time of a file outside the destination directory, or expose the contents of that file within the extracted tree.

In CPython 3.13 and earlier, the tarfile module's data and tar extraction filters are vulnerable to crafted archives containing a hard link to a symbolic link. Such archives may cause extraction to modify the permissions or modification time of a file outside the destination directory, or expose the contents of that file within the extracted tree.

In CPython 3.13 and earlier, the tarfile module's data and tar extraction filters are vulnerable to crafted archives containing a hard link to a symbolic link. Such archives may cause extraction to modify the permissions or modification time of a file outside the destination directory, or expose the contents of that file within the extracted tree.

In CPython 3.13 and earlier, the tarfile module's data and tar extraction filters are vulnerable to crafted archives containing a hard link to a symbolic link. Such archives may cause extraction to modify the permissions or modification time of a file outside the destination directory, or expose the contents of that file within the extracted tree.

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. This could crash the process when processing untrusted data.

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 programs are potentially able to modify permissions of files referenced by symlinks in some circumstances.

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 programs are potentially able to modify permissions of files referenced by symlinks in some circumstances.

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 programs are potentially able to modify permissions of files referenced by symlinks in some circumstances.

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 programs are potentially able to modify permissions of files referenced by symlinks in some circumstances.

ssl.SSLContext.wrapbio() didn't require the serverhostname argument to not be None if ssl.SSLContext.checkhostname was set. Due to a missing parameter check in SSLObject, if the serverhostname argument isn't supplied then hostname verification would be silently skipped.

This defect could lead to programs where certificate hostname verification appeared to be succeeding with SSLContext.checkhostname = True and no ValueError being raised due to misconfiguration.

If the program passes a serverhostname value that isn't an empty string or None to any of these APIs then certificate hostname verification proceeds as expected and the program is not affected by this vulnerability.

Mitigating this vulnerability doesn't require updating Python or applying the patch. To mitigate, pass a valid non-None and non-empty serverhostname value to SSLContext.wrapbio(), asyncio.createconnection(), or asyncio.loop.starttls() and certificate hostname verification will proceed as expected. Upgrading to the latest version of Python or applying the patch only changes the behavior from silently skipping hostname verification to raising a ValueError, similar to SSLContext.wrapsocket(), when serverhostname isn't supplied.

The “ipaddress” module contained incorrect information about whether certain IPv4 and IPv6 addresses were designated as “globally reachable” or “private”. This affected the isprivate and isglobal properties of the ipaddress.IPv4Address, ipaddress.IPv4Network, ipaddress.IPv6Address, and ipaddress.IPv6Network classes, where values wouldn’t be returned in accordance with the latest information from the IANA Special-Purpose Address Registries.

CPython 3.12.4 and 3.13.0a6 contain updated information from these registries and thus have the intended behavior.

The “ipaddress” module contained incorrect information about whether certain IPv4 and IPv6 addresses were designated as “globally reachable” or “private”. This affected the isprivate and isglobal properties of the ipaddress.IPv4Address, ipaddress.IPv4Network, ipaddress.IPv6Address, and ipaddress.IPv6Network classes, where values wouldn’t be returned in accordance with the latest information from the IANA Special-Purpose Address Registries.

CPython 3.12.4 and 3.13.0a6 contain updated information from these registries and thus have the intended behavior.

The “ipaddress” module contained incorrect information about whether certain IPv4 and IPv6 addresses were designated as “globally reachable” or “private”. This affected the isprivate and isglobal properties of the ipaddress.IPv4Address, ipaddress.IPv4Network, ipaddress.IPv6Address, and ipaddress.IPv6Network classes, where values wouldn’t be returned in accordance with the latest information from the IANA Special-Purpose Address Registries.

CPython 3.12.4 and 3.13.0a6 contain updated information from these registries and thus have the intended behavior.

The “ipaddress” module contained incorrect information about whether certain IPv4 and IPv6 addresses were designated as “globally reachable” or “private”. This affected the isprivate and isglobal properties of the ipaddress.IPv4Address, ipaddress.IPv4Network, ipaddress.IPv6Address, and ipaddress.IPv6Network classes, where values wouldn’t be returned in accordance with the latest information from the IANA Special-Purpose Address Registries.

CPython 3.12.4 and 3.13.0a6 contain updated information from these registries and thus have the intended behavior.

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.

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.

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.

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.

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.

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.

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.

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

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

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

A defect was discovered in the Python “ssl” module where there is a memory race condition with the ssl.SSLContext methods “certstorestats()” and “getcacerts()”. The race condition can be triggered if the methods are called at the same time as certificates are loaded into the SSLContext, such as during the TLS handshake with a certificate directory configured. This issue is fixed in CPython 3.10.14, 3.11.9, 3.12.3, and 3.13.0a5.

A defect was discovered in the Python “ssl” module where there is a memory race condition with the ssl.SSLContext methods “certstorestats()” and “getcacerts()”. The race condition can be triggered if the methods are called at the same time as certificates are loaded into the SSLContext, such as during the TLS handshake with a certificate directory configured. This issue is fixed in CPython 3.10.14, 3.11.9, 3.12.3, and 3.13.0a5.