CVE-2026-3446

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.

CVSS 4.0

6.0CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS

0.2% chance of exploitation in the next 30 days; higher than 8% of CVEs (scores of 2026-10-26)

CWE

CWE-345

Published

2026-04-10

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

References

• https://github.com/python/cpython/commit/1f9958f909c1b41a4ffc0b613ef8ec8fa5e7c474
• https://github.com/python/cpython/commit/4561f6418a691b3e89aef0901f53fe0dfb7f7c0e
• https://github.com/python/cpython/commit/e31c55121620189a0d1a07b689762d8ca9c1b7fa
• https://github.com/python/cpython/issues/145264
• https://github.com/python/cpython/pull/145267

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