Base64 decoding stops at first padded quad by default
CVE-2026-3446 is fixed in 22 products on 2 platforms, first by Python 3.13 3.13.13, released April 7, 2026. 9 other affected products have no fix yet. It is not reported as exploited. Patch Radar priority: Routine.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| Python 3.13 | 3.13.13 | Python 3.13 3.13.13 | Apr 7, 2026 |
| Python 3.14 | 3.14.4 | Python 3.14 3.14.4 | Apr 7, 2026 |
| Linux | |||
| python · sles 15.7 | 2.7.18-150000.117.1 | SUSE-SU-2026:1503-1 | Apr 20, 2026 |
| python-base · sles 15.7 | 2.7.18-150000.117.1 | SUSE-SU-2026:1503-1 | Apr 20, 2026 |
| python-unversioned-command · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3 · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3 · opensuse-leap 16.0 | 3.13.14-160000.1.1 | OPENSUSE-SU-2026:21459-1 | Jul 28, 2026 |
| python3 · sles 15.6 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3 · sles 15.7 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3-core · sles 15.6 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3-core · sles 15.7 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3-debug · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3-devel · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3-idle · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3-libs · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3-test · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3-tkinter · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3.13 · Debian 13.5 (trixie) | 3.13.5-2+deb13u2 | DEBIAN-CVE-2026-3446 | Apr 10, 2026 |
| python3.14 · Debian 14 | 3.14.4-1 | DEBIAN-CVE-2026-3446 | Apr 10, 2026 |
| python3.9-debuginfo · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python3.9-debugsource · amzn 2023 | 3.9.25-1.amzn2023.0.7 | ALAS2023-2026-1933 | Jul 6, 2026 |
| python313 · opensuse-leap 16.0 | 3.13.14-160000.1.1 | OPENSUSE-SU-2026:21459-1 | Jul 28, 2026 |
| python313 · sles 15.7 | 3.13.13-150700.4.50.1 | SUSE-SU-2026:2464-1 | Jun 19, 2026 |
| python313-core · opensuse-leap 16.0 | 3.13.14-160000.1.1 | OPENSUSE-SU-2026:21459-1 | Jul 28, 2026 |
| python313-core · sles 15.7 | 3.13.13-150700.4.50.1 | SUSE-SU-2026:2464-1 | Jun 19, 2026 |
| python313-documentation · opensuse-leap 16.0 | 3.13.14-160000.1.1 | OPENSUSE-SU-2026:21459-1 | Jul 28, 2026 |
| python313-nogil · opensuse-leap 16.0 | 3.13.14-160000.1.1 | OPENSUSE-SU-2026:21459-1 | Jul 28, 2026 |
| python313-nogil-nogil-core · opensuse-leap 16.0 | 3.13.14-160000.1.1 | OPENSUSE-SU-2026:21459-1 | Jul 28, 2026 |
| No fix yet | |||
| Python 2 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.10 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.11 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.12 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.5 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.6 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.7 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.8 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.9 (Windows apps) | No fix yet | no-fix | n/a |
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