8000 binascii.a2b_base64 strict mode accepts invalid base64 input · Issue #118314 · python/cpython · GitHub
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zhangyoufu opened this issue Apr 26, 2024 · 0 comments
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binascii.a2b_base64 strict mode accepts invalid base64 input #118314

zhangyoufu opened this issue Apr 26, 2024 · 0 comments
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type-bug An unexpected behavior, bug, or error

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@zhangyoufu
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zhangyoufu commented Apr 26, 2024 •
edited by bedevere-app bot
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Bug report

Bug description:

>>> import binascii
>>> f = lambda s: binascii.a2b_base64(s, strict_mode=True)
>>> f('AAAA')
b'\x00\x00\x00'
>>> f('AAAA=')
b'\x00\x00\x00'
>>> f('AAAA==')
b'\x00\x00\x00'
>>> f('AAAA===')
b'\x00\x00\x00'
>>> f('AAAA====')
b'\x00\x00\x00'
>>> f('AAAA=====')
b'\x00\x00\x00'

Doc/library/binascii.rst defines that a valid base64 "Contains no excess data after padding (including excess padding, newlines, etc.)". However, current implement does not handle the edge case of excess padding after no padding.

CPython versions tested on:

3.12

Operating systems tested on:

macOS

Linked PRs
@zhangyoufu zhangyoufu added the type-bug An unexpected behavior, bug, or error label Apr 26, 2024
@bedevere-app bedevere-app bot mentioned this issue Apr 26, 2024
Merged
@zhangyoufu zhangyoufu changed the title binascii.a2b_base64 with strict_mode=True accepts invalid base64 input binascii.a2b_base64 strict mode accepts invalid base64 input Apr 26, 2024
encukou pushed a commit that referenced this issue May 7, 2024
@zhangyoufu @terryjreedy @eendebakpt
gh-118314: Fix padding edge case in binascii.a2b_base64 strict mode (G…
fe47d9b 
…H-118320)

Fix an edge case in `binascii.a2b_base64` strict mode, where
excessive padding was not detected when no padding is necessary.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
miss-islington pushed a commit to miss-islington/cpython that referenced this issue May 7, 2024
@zhangyoufu @terryjreedy
@eendebakpt @miss-islington
pythongh-118314: Fix padding edge case in binascii.a2b_base64 strict …
8ee2b08 
…mode (pythonGH-118320)

Fix an edge case in `binascii.a2b_base64` strict mode, where
excessive padding was not detected when no padding is necessary.

(cherry picked from commit fe47d9b)

Co-authored-by: Youfu Zhang <1315097+zhangyoufu@users.noreply.github.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
@bedevere-app bedevere-app bot mentioned this issue May 7, 2024
Merged
encukou pushed a commit that referenced this issue May 7, 2024
@miss-islington @zhangyoufu
@terryjreedy @eendebakpt
[3.12] gh-118314: Fix padding edge case in binascii.a2b_base64 strict…
56c61cc 
… mode (GH-118320) (GH-118691)

gh-118314: Fix padding edge case in binascii.a2b_base64 strict mode (GH-118320)

Fix an edge case in `binascii.a2b_base64` strict mode, where
excessive padding was not detected when no padding is necessary.

(cherry picked from commit fe47d9b)

Co-authored-by: Youfu Zhang <1315097+zhangyoufu@users.noreply.github.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
@encukou encukou closed this as completed May 7, 2024
SonicField pushed a commit to SonicField/cpython that referenced this issue May 8, 2024
@zhangyoufu @terryjreedy
@eendebakpt @SonicField
pythongh-118314: Fix padding edge case in binascii.a2b_base64 strict …
a3213b3 
…mode (pythonGH-118320)

Fix an edge case in `binascii.a2b_base64` strict mode, where
excessive padding was not detected when no padding is necessary.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
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