CVE-2026-4519

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().

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 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.(CVE-2026-2297)

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().(CVE-2026-4519)

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 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.(CVE-2026-2297)

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().(CVE-2026-4519)

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 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.(CVE-2026-2297)

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().(CVE-2026-4519)

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 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.(CVE-2026-2297)

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().(CVE-2026-4519)

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• cpython: wsgiref.headers.Headers allows header newline injection in Python (CVE-2026-0865)

• cpython: CPython: Logging Bypass in Legacy .pyc File Handling (CVE-2026-2297)

• cpython: Incomplete control character validation in http.cookies (CVE-2026-3644)

• cpython: Stack overflow parsing XML with deeply nested DTD content models (CVE-2026-4224)

• python: Python: Command-line option injection in webbrowser.open() via crafted URLs (CVE-2026-4519)

• python: Python: HTTP header injection via CR/LF in proxy tunnel headers (CVE-2026-1502)

• python: Python: Arbitrary code execution or information disclosure via use-after-free in decompression modules (CVE-2026-6100)

• python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API (CVE-2026-4786)

• python: Python: Information disclosure and arbitrary code execution via remote debugging with a malicious process. (CVE-2026-5713)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• expat: libexpat in Expat allows attackers to trigger large dynamic memory allocations via a small document that is submitted for parsing (CVE-2025-59375)

• python: Quadratic complexity in os.path.expandvars() with user-controlled template (CVE-2025-6075)

• cpython: Out-of-memory when loading Plist (CVE-2025-13837)

• cpython: Header injection via newlines in data URL mediatype in Python (CVE-2025-15282)

• cpython: Header injection in http.cookies.Morsel in Python (CVE-2026-0672)

• cpython: CPython: Logging Bypass in Legacy .pyc File Handling (CVE-2026-2297)

• cpython: Incomplete control character validation in http.cookies (CVE-2026-3644)

• cpython: Stack overflow parsing XML with deeply nested DTD content models (CVE-2026-4224)

• python: Python: Command-line option injection in webbrowser.open() via crafted URLs (CVE-2026-4519)

• python: Python: HTTP header injection via CR/LF in proxy tunnel headers (CVE-2026-1502)

• python: Python: Arbitrary code execution or information disclosure via use-after-free in decompression modules (CVE-2026-6100)

• python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API (CVE-2026-4786)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• python: Python: Command-line option injection in webbrowser.open() via crafted URLs (CVE-2026-4519)

• python: Python: Arbitrary code execution or information disclosure via use-after-free in decompression modules (CVE-2026-6100)

• python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API (CVE-2026-4786)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• cpython: wsgiref.headers.Headers allows header newline injection in Python (CVE-2026-0865)

• cpython: CPython: Logging Bypass in Legacy .pyc File Handling (CVE-2026-2297)

• cpython: Incomplete control character validation in http.cookies (CVE-2026-3644)

• cpython: Stack overflow parsing XML with deeply nested DTD content models (CVE-2026-4224)

• python: Python: Command-line option injection in webbrowser.open() via crafted URLs (CVE-2026-4519)

• python: Python: HTTP header injection via CR/LF in proxy tunnel headers (CVE-2026-1502)

• python: Python: Arbitrary code execution or information disclosure via use-after-free in decompression modules (CVE-2026-6100)

• python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API (CVE-2026-4786)

• python: Python: Information disclosure and arbitrary code execution via remote debugging with a malicious process. (CVE-2026-5713)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• expat: libexpat in Expat allows attackers to trigger large dynamic memory allocations via a small document that is submitted for parsing (CVE-2025-59375)

• python: Quadratic complexity in os.path.expandvars() with user-controlled template (CVE-2025-6075)

• cpython: Out-of-memory when loading Plist (CVE-2025-13837)

• cpython: Header injection via newlines in data URL mediatype in Python (CVE-2025-15282)

• cpython: Header injection in http.cookies.Morsel in Python (CVE-2026-0672)

• cpython: CPython: Logging Bypass in Legacy .pyc File Handling (CVE-2026-2297)

• cpython: Incomplete control character validation in http.cookies (CVE-2026-3644)

• cpython: Stack overflow parsing XML with deeply nested DTD content models (CVE-2026-4224)

• python: Python: Command-line option injection in webbrowser.open() via crafted URLs (CVE-2026-4519)

• python: Python: HTTP header injection via CR/LF in proxy tunnel headers (CVE-2026-1502)

• python: Python: Arbitrary code execution or information disclosure via use-after-free in decompression modules (CVE-2026-6100)

• python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API (CVE-2026-4786)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• python: Python: Command-line option injection in webbrowser.open() via crafted URLs (CVE-2026-4519)

• python: Python: Arbitrary code execution or information disclosure via use-after-free in decompression modules (CVE-2026-6100)

• python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API (CVE-2026-4786)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems.

Security Fix(es):

• python: Python: Command-line option injection in webbrowser.open() via crafted URLs (CVE-2026-4519)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.