BIT-PYTHON-2025-12781 base64.b64decode() always accepts "+/" characters, despite setting altchars

When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. Th...

BIT-PYTHON-MIN-2025-12781 base64.b64decode() always accepts "+/" characters, despite setting altchars

When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. Th...

CVE-2025-12781

A flaw was found in the base64 module in the Python standard library. The b64decode, standardb64decode and urlsafeb64decode functions will always accept the '+' and '/' characters even when an alternative base64 alphabet is specified via the altchars parameter that excludes them. This input...

Linux Distros Unpatched Vulnerability : CVE-2025-12781

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the base64 module the characters +/ will always be accepted, regardless...

DEBIAN-CVE-2025-12781

When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. Th...

CVE-2025-12781

When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. Th...

CVE-2025-12781

When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. Th...

CVE-2025-12781 base64.b64decode() always accepts "+/" characters, despite setting altchars

When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. Th...

EUVD-2026-3598

When passing data to the b64decode, standardb64decode, and urlsafeb64decode functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. Th...

CVE-2025-12781

CVE-2025-12781 concerns the base64 module in Python, where b64decode(), standard_b64decode(), and urlsafe_b64decode() historically accept the characters "+/" regardless of the altchars parameter. The connected sources confirm this behavior and note that newer RFCs recommend restricting to the spe...