PT-2026-32017 · Python · Cpython

Serhiy Storchaka · Published 2026-04-10 · Updated 2026-04-10 · CVE-2026-3446

NVD

CVSS v4.0

6.0

Medium

AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

When calling base64.b64decode() or related functions the decoding process would stop after encountering the first padded quad regardless of whether there was more information to be processed. This can lead to data being accepted which may be processed differently by other implementations. Use "validate=True" to enable stricter processing of base64 data.

Fix

Related Identifiers

CVE-2026-3446

Affected Products

Cpython

References · 7

• https://nvd.nist.gov/vuln/detail/CVE-2026-3446 · Security Note
• https://mail.python.org/archives/list/[e-mail]/thread/F5ZT5ICGJ6CKXVUJ34YBVY7WOZ5SHG53 · Vendor Advisory
• https://github.com/python/cpython/commit/4561f6418a691b3e89aef0901f53fe0dfb7f7c0e · Patch
• https://github.com/python/cpython/pull/145267 · Patch
• https://github.com/python/cpython/commit/1f9958f909c1b41a4ffc0b613ef8ec8fa5e7c474 · Patch
• https://github.com/python/cpython/commit/e31c55121620189a0d1a07b689762d8ca9c1b7fa · Patch
• https://github.com/python/cpython/issues/145264 · Note