// For flags

CVE-2026-3446

Base64 decoding stops at first padded quad by default

Severity Score

6.0
*CVSS v4

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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.

*Credits: Serhiy Storchaka
CVSS Scores
Attack Vector
Network
Attack Complexity
High
Attack Requirements
Present
Privileges Required
Low
User Interaction
None
System
Vulnerable | Subsequent
Confidentiality
None
None
Integrity
High
None
Availability
None
None
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2026-03-02 CVE Reserved
  • 2026-04-10 CVE Published
  • 2026-04-13 CVE Updated
  • 2026-05-12 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-345: Insufficient Verification of Data Authenticity
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Python Software Foundation
Search vendor "Python Software Foundation"
 CPython
Search vendor "Python Software Foundation" for product "CPython"
 < 3.13.13
Search vendor "Python Software Foundation" for product "CPython" and version " < 3.13.13"
en
Affected
Python Software Foundation
Search vendor "Python Software Foundation"
 CPython
Search vendor "Python Software Foundation" for product "CPython"
 >= 3.14.0 < 3.14.4
Search vendor "Python Software Foundation" for product "CPython" and version " >= 3.14.0 < 3.14.4"
en
Affected