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VulnerabilityPublished Updated

CVE-2026-3446: Python Software Foundation CPython · CWE-345

Affects Python Software Foundation CPythonSource CVE Database V5

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Not known to be exploited · CVSS 6.0 Medium · fixed in 3.15.0a8 : update Python Software Foundation CPython when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score
6.0Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.15.0a8, 3.14.4, 3.13.13
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade Python Software Foundation CPython to 3.15.0a8, 3.14.4 or 3.13.13.

Affected software

ProductAffectedFixed in
Python Software FoundationCPythonAffected
  • >=3.15.0a1 <3.15.0a8
Fixed in
  • 3.15.0a8
Python Software FoundationCPythonAffected
  • >=3.14.0 <3.14.4
Fixed in
  • 3.14.4
Python Software FoundationCPythonAffected
  • <3.13.13
Fixed in
  • 3.13.13
PyPIcpythonpkg:pypi/cpythonOther threatsAffected
  • =0
  • =3.14.0
  • =3.15.0
Fixed in–
GitHubCPythonpkg:github/CPythonOther threatsAffected
  • <3.13.13
  • >=3.14.0 <3.14.4
  • >=3.15.0a1 <3.15.0a8
Fixed in
  • 3.13.13
  • 3.14.4
  • 3.15.0a8

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Users are advised to use the "validate=True" parameter in base64.b64decode() calls to enable stricter validation of base64 data, which mitigates the issue by rejecting improperly padded input.

Description

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.

References

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