CVE-2026-18503

Python combines remarkable power with very clear syntax. It has modules, classes, exceptions, very high level dynamic data types, and dynamic typing. There are interfaces to many system calls and libraries, as well as to various windowing systems. New built-in modules are easily written in C or C++ (or other languages, depending on the chosen implementation). Python is also usable as an extension language for applications written in other languages that need easy-to-use scripting or automation interfaces.

Security Fix(es):

The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a requested URL. Credentials added for an https:// URL were also used for requests to the same host over http://, so an attacker able to redirect or downgrade a client to plain HTTP (for example, via an HTTPS-to-HTTP redirect or an on-path position) could capture credentials in cleartext. Credentials added for http:// URLs could likewise be sent over https://. Credential matching is now scoped by URL scheme. Credentials registered with a URL that includes a scheme are only used for requests with the same scheme. Credentials registered with a bare authority (such as example.com or example.com:8080) continue to match any scheme, preserving compatibility with existing code, including proxy authentication.(CVE-2026-15806)

The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the in_table_b2() function of the "stringprep" module. This only affects domain names containing characters that were not previously registered or had their Unicode attributes such as case-folding behavior updated since Unicode 3.2.0.(CVE-2026-17084)

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().(CVE-2026-18503)

The tarfile module's tar and data extraction filters created directories outside the destination for members whose name leaves the destination and returns to it, such as ../evil/../dest/sub/file. The containment check used the resolved path, but intermediate directories were created from the name as given. Only empty directories are created outside the destination. Member contents are still extracted inside it. To return to the destination the member's name must contain the destination directory's own final component, so extraction into a secure randomised directory is not affected. This affects POSIX platforms only. On Windows, .. components are collapsed before the path reaches the filesystem, so the directories outside the destination are never created.(CVE-2026-19672)

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.(CVE-2026-82049)

When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link. For one of the calls, the return value was ignored. Instead, the member should be skipped if either call returns None.(CVE-2026-87910)

Python combines remarkable power with very clear syntax. It has modules, classes, exceptions, very high level dynamic data types, and dynamic typing. There are interfaces to many system calls and libraries, as well as to various windowing systems. New built-in modules are easily written in C or C++ (or other languages, depending on the chosen implementation). Python is also usable as an extension language for applications written in other languages that need easy-to-use scripting or automation interfaces.

Security Fix(es):

The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a requested URL. Credentials added for an https:// URL were also used for requests to the same host over http://, so an attacker able to redirect or downgrade a client to plain HTTP (for example, via an HTTPS-to-HTTP redirect or an on-path position) could capture credentials in cleartext. Credentials added for http:// URLs could likewise be sent over https://. Credential matching is now scoped by URL scheme. Credentials registered with a URL that includes a scheme are only used for requests with the same scheme. Credentials registered with a bare authority (such as example.com or example.com:8080) continue to match any scheme, preserving compatibility with existing code, including proxy authentication.(CVE-2026-15806)

The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the in_table_b2() function of the "stringprep" module. This only affects domain names containing characters that were not previously registered or had their Unicode attributes such as case-folding behavior updated since Unicode 3.2.0.(CVE-2026-17084)

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().(CVE-2026-18503)

The tarfile module's tar and data extraction filters created directories outside the destination for members whose name leaves the destination and returns to it, such as ../evil/../dest/sub/file. The containment check used the resolved path, but intermediate directories were created from the name as given. Only empty directories are created outside the destination. Member contents are still extracted inside it. To return to the destination the member's name must contain the destination directory's own final component, so extraction into a secure randomised directory is not affected. This affects POSIX platforms only. On Windows, .. components are collapsed before the path reaches the filesystem, so the directories outside the destination are never created.(CVE-2026-19672)

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.(CVE-2026-82049)

When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link. For one of the calls, the return value was ignored. Instead, the member should be skipped if either call returns None.(CVE-2026-87910)

Python combines remarkable power with very clear syntax. It has modules, classes, exceptions, very high level dynamic data types, and dynamic typing. There are interfaces to many system calls and libraries, as well as to various windowing systems. New built-in modules are easily written in C or C++ (or other languages, depending on the chosen implementation). Python is also usable as an extension language for applications written in other languages that need easy-to-use scripting or automation interfaces.

Security Fix(es):

The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a requested URL. Credentials added for an https:// URL were also used for requests to the same host over http://, so an attacker able to redirect or downgrade a client to plain HTTP (for example, via an HTTPS-to-HTTP redirect or an on-path position) could capture credentials in cleartext. Credentials added for http:// URLs could likewise be sent over https://. Credential matching is now scoped by URL scheme. Credentials registered with a URL that includes a scheme are only used for requests with the same scheme. Credentials registered with a bare authority (such as example.com or example.com:8080) continue to match any scheme, preserving compatibility with existing code, including proxy authentication.(CVE-2026-15806)

The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the in_table_b2() function of the "stringprep" module. This only affects domain names containing characters that were not previously registered or had their Unicode attributes such as case-folding behavior updated since Unicode 3.2.0.(CVE-2026-17084)

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().(CVE-2026-18503)

The tarfile module's tar and data extraction filters created directories outside the destination for members whose name leaves the destination and returns to it, such as ../evil/../dest/sub/file. The containment check used the resolved path, but intermediate directories were created from the name as given. Only empty directories are created outside the destination. Member contents are still extracted inside it. To return to the destination the member's name must contain the destination directory's own final component, so extraction into a secure randomised directory is not affected. This affects POSIX platforms only. On Windows, .. components are collapsed before the path reaches the filesystem, so the directories outside the destination are never created.(CVE-2026-19672)

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.(CVE-2026-82049)

When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link. For one of the calls, the return value was ignored. Instead, the member should be skipped if either call returns None.(CVE-2026-87910)

Python combines remarkable power with very clear syntax. It has modules, classes, exceptions, very high level dynamic data types, and dynamic typing. There are interfaces to many system calls and libraries, as well as to various windowing systems. New built-in modules are easily written in C or C++ (or other languages, depending on the chosen implementation). Python is also usable as an extension language for applications written in other languages that need easy-to-use scripting or automation interfaces.

Security Fix(es):

The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a requested URL. Credentials added for an https:// URL were also used for requests to the same host over http://, so an attacker able to redirect or downgrade a client to plain HTTP (for example, via an HTTPS-to-HTTP redirect or an on-path position) could capture credentials in cleartext. Credentials added for http:// URLs could likewise be sent over https://. Credential matching is now scoped by URL scheme. Credentials registered with a URL that includes a scheme are only used for requests with the same scheme. Credentials registered with a bare authority (such as example.com or example.com:8080) continue to match any scheme, preserving compatibility with existing code, including proxy authentication.(CVE-2026-15806)

The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the in_table_b2() function of the "stringprep" module. This only affects domain names containing characters that were not previously registered or had their Unicode attributes such as case-folding behavior updated since Unicode 3.2.0.(CVE-2026-17084)

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().(CVE-2026-18503)

The tarfile module's tar and data extraction filters created directories outside the destination for members whose name leaves the destination and returns to it, such as ../evil/../dest/sub/file. The containment check used the resolved path, but intermediate directories were created from the name as given. Only empty directories are created outside the destination. Member contents are still extracted inside it. To return to the destination the member's name must contain the destination directory's own final component, so extraction into a secure randomised directory is not affected. This affects POSIX platforms only. On Windows, .. components are collapsed before the path reaches the filesystem, so the directories outside the destination are never created.(CVE-2026-19672)

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.(CVE-2026-82049)

When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link. For one of the calls, the return value was ignored. Instead, the member should be skipped if either call returns None.(CVE-2026-87910)

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().

• CVE-2026-6879: xml.etree.ElementPath: avoid quadratic behaviour in XPath index predicates ([1], [last()], [last()-N])
• CVE-2026-18503: fix quadratic time in csv.Sniffer for quoted fields
• Backport upstream 3.11 fixes the CVE-2026-18503 fix relies on or completes: correct matching of possessive quantifiers in the re engine (gh-106052, gh-100061) and super-linear doublequote detection in csv.Sniffer (gh-109638)

These are all security issues fixed in the python315-3.15.0~rc2-1.1 package on the GA media of openSUSE Tumbleweed.

These are all security issues fixed in the python313-3.13.15-1.1 package on the GA media of openSUSE Tumbleweed.

Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().

This update for python313 fixes the following issues:

Security issues fixed:

• CVE-2026-6879: quadratic behavior in xml.etree.ElementPath index predicates can lead to a denial of service via high CPU usage (bsc#1273148).
• CVE-2026-9669: crafted input can cause a stack buffer overflow (bsc#1267974).
• CVE-2026-17084: [Security-announce][] StringPrep algorithm considered (bsc#1276226).
• CVE-2026-18503: attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU (bsc#1274683).

Non security issue fixed:

• Conflicts between different versions of Python (bsc#1258364).
• Updated to version 3.13.15

This update for python fixes the following issues:

• CVE-2026-6879: quadratic behavior in xml.etree.ElementPath index predicates can lead to a denial of service via high CPU usage (bsc#1273148).
• CVE-2026-9669: crafted input can cause a stack buffer overflow (bsc#1267974).
• CVE-2026-15806: urllib.request.HTTPPasswordMgr credentials for one URL scheme sent over another scheme (bsc#1276223).
• CVE-2026-17084: StringPrep algorithm considered Unicode codepoint attributes outside Unicode 3.2.0 (bsc#1276226).
• CVE-2026-18503: attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU (bsc#1274683).
• CVE-2026-19672: The tarfile module's tar and data extraction filters created directories outside the destination for members whose name leaves the destination and retu (bsc#1276227).

Changes for python:

• Update bundled setuptools wheels to setuptools-40.6.2-py2.py3-none-any.whl (bsc#1276903)

This update for python fixes the following issues:

• CVE-2026-6879: quadratic behavior in xml.etree.ElementPath index predicates can lead to a denial of service via high CPU usage (bsc#1273148).
• CVE-2026-9669: crafted input can cause a stack buffer overflow (bsc#1267974).
• CVE-2026-15806: urllib.request.HTTPPasswordMgr credentials for one URL scheme sent over another scheme (bsc#1276223).
• CVE-2026-17084: StringPrep algorithm considered Unicode codepoint attributes outside Unicode 3.2.0 (bsc#1276226).
• CVE-2026-18503: attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU (bsc#1274683).
• CVE-2026-19672: The tarfile module's tar and data extraction filters created directories outside the destination for members whose name leaves the destination and retu (bsc#1276227).

Changes for python:

• Update bundled setuptools wheels to setuptools-40.6.2-py2.py3-none-any.whl (bsc#1276903)

This update for python36 fixes the following issues:

Security issues fixed:

• CVE-2026-1703: files may be extracted outside the installation directory when installing and extracting maliciously crafted wheel archives (bsc#1274743).
• CVE-2026-3219: pip doesn't reject concatenated ZIP (bsc#1262429).
• CVE-2026-3446: Base64 decoding stops at first padded quad by default (bsc#1261970).
• CVE-2026-3479: python: improper resource argument validation can allow path traversal (bsc#1259989).
• CVE-2026-4224: C stack overflow when parsing XML with deeply nested DTD content models (bsc#1259735).
• CVE-2026-6879: quadratic behavior in xml.etree.ElementPath index predicates can lead to a denial of service via high CPU usage (bsc#1273148).
• CVE-2026-9669: crafted input can cause a stack buffer overflow (bsc#1267974).
• CVE-2026-13346: Arbitrary file installation via malicious package indexes (bsc#1273090 bsc#1273091 bsc#1273094).
• CVE-2026-15310: memory exhaustion in zipfile in bzip2/LZMA/Zstandard decompression (bsc#1277111).
• CVE-2026-15806: urllib.request.HTTPPasswordMgr credentials for one URL scheme sent over another scheme (bsc#1276223).
• CVE-2026-17084: StringPrep algorithm considered Unicode codepoint attributes outside Unicode 3.2.0 (bsc#1276226).
• CVE-2026-18503: attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU (bsc#1274683).
• CVE-2026-19672: tarfile extraction filter bypass allows creation of directories outside the destination (bsc#1276227).
• CVE-2026-82049: tarfile extraction filters mishandle archives containing a hard link to a symbolic link, allowing file modification and content disclosure (bsc#1280459).

Non security issue fixed:

• Update bundled setuptools wheels to setuptools-44.1.1-py2.py3-none-any.whl (bsc#1277271)

This update for python3, python3-base, python3-doc fixes the following issues:

Security issues fixed:

• CVE-2026-6879: quadratic behavior in xml.etree.ElementPath index predicates can lead to a denial of service via high CPU usage (bsc#1273148).
• CVE-2026-9669: crafted input can cause a stack buffer overflow (bsc#1267974).
• CVE-2026-15310: memory exhaustion in zipfile in bzip2/LZMA/Zstandard decompression (bsc#1277111).
• CVE-2026-15806: urllib.request.HTTPPasswordMgr credentials for one URL scheme sent over another scheme (bsc#1276223).
• CVE-2026-17084: StringPrep algorithm considered Unicode codepoint attributes outside Unicode 3.2.0 (bsc#1276226).
• CVE-2026-18503: attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU (bsc#1274683).
• CVE-2026-19672: tarfile extraction filter bypass allows creation of directories outside the destination (bsc#1276227).
• CVE-2026-82049: tarfile extraction filters mishandle archives containing a hard link to a symbolic link, allowing file modification and content disclosure (bsc#1280459).

Changes for python3:

• Update bundled setuptools wheels to setuptools-40.6.2 (bsc#1276903).

This update for python3 fixes the following issues:

Security issues fixed:

• CVE-2026-0864: improper handling of line-ending characters can lead to configuration file injection when the configparser module is used (bsc#1269066).
• CVE-2026-1703: files may be extracted outside the installation directory when installing and extracting maliciously crafted wheel archives (bsc#1257599 bsc#1274743).
• CVE-2026-3219: pip doesn't reject concatenated ZIP (bsc#1262429 bsc#1262467).
• CVE-2026-3276: quadratic complexity in unicodedata.normalize() can lead to DoS when processing specially crafted Unicode input (bsc#1267581).
• CVE-2026-3446: Base64 decoding stops at first padded quad by default (bsc#1261970).
• CVE-2026-3479: python: improper resource argument validation can allow path traversal (bsc#1259989).
• CVE-2026-4224: C stack overflow when parsing XML with deeply nested DTD content models (bsc#1259735).
• CVE-2026-4360: in the Tarfile.extract() function, the filter parameter is not passed properly when extracting hardlinks (bsc#1269959).
• CVE-2026-6357: pip self-update functionality can import newly installed modules after wheel installation (bsc#1263442 bsc#1263443).
• CVE-2026-6879: quadratic behavior in xml.etree.ElementPath index predicates can lead to a denial of service via high CPU usage (bsc#1273148).
• CVE-2026-7210: xml.parsers.expat and xml.etree.ElementTree use insufficient entropy for Expat hash-flooding protection (bsc#1264962).
• CVE-2026-7774: tarfile.data_filter path traversal bypass allows writing outside the extraction directory (bsc#1267821).
• CVE-2026-8328: ftpcp() does not use actual peer address and trusts server-supplied PASV host address (bsc#1265268).
• CVE-2026-8643: Path traversal via malicious entry point name in pip wheel installation allows arbitrary file overwrite (bsc#1266669).
• CVE-2026-9669: crafted input can cause a stack buffer overflow (bsc#1267974).
• CVE-2026-11940: tarfile extraction filter bypass via a crafted archive allows escaping the destination directory and enables arbitrary file reads and writes (bsc#1268977).
• CVE-2026-11972: infinite loop due to improper EOF handling in the tarfile module streaming mode can lead to DoS (bsc#1269788).
• CVE-2026-13346: Arbitrary file installation via malicious package indexes (bsc#1273090 bsc#1273091 bsc#1273094).
• CVE-2026-15308: Incremental HTMLParser allows CPU-exhaustion DoS via repeated unterminated markup declarations (bsc#1271192).
• CVE-2026-15310: memory exhaustion in zipfile in bzip2/LZMA/Zstandard decompression (bsc#1277111).
• CVE-2026-15806: urllib.request.HTTPPasswordMgr credentials for one URL scheme sent over another scheme (bsc#1276223).
• CVE-2026-17084: StringPrep algorithm considered Unicode codepoint attributes outside Unicode 3.2.0 (bsc#1276226).
• CVE-2026-18503: attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU (bsc#1274683).
• CVE-2026-19672: tarfile extraction filter bypass allows creation of directories outside the destination (bsc#1276227).
• CVE-2026-82049: tarfile extraction filters mishandle archives containing a hard link to a symbolic link, allowing file modification and content disclosure (bsc#1280459).

Non security issue fixed:

• Fix an error that returned non-zero exit status 1 (bsc#1277271).
• Fix regression in http.cookies (bsc#1263083).
• Update bundled pip wheels to pip-20.0.2-py2.py3-none-any.whl.