All vulnerabilities

Servers and applications

CVE-2025-12781

When passing data to the b64decode(), standard_b64decode(), and urlsafe_b64decode() 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. This behavior matches what is recommended in earlier base64 RFCs, but newer RFCs now recommend…

Severity
Medium 6.3
Published
21 Jan 2026
Last changed
17 Jun 2026
Added to UpHeron
21 Oct 2026
Fixed in
3.13.10, 3.14.1
Sources
NVD

Affected software

SoftwareAffected versions
PythonServers and applications · cpe:a:python:python
  • Every version before 3.13.10
  • From 3.14.0 before 3.14.1
  • Version 3.15.0-alpha1

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2025-12781
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2025-12781