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HighVulnerabilityupdated 26 Oct 2026, 13:10 UTC

Python: several security flaws fixed in new releases

Several weaknesses in the Python language runtime could let outsiders crash programs, read or change data, or get around some protections. Updating Python closes them.

Fixed in Python 3.15.1, 3.14.9 and 3.13.17Official, 2 sources
SeverityHighVulnerability
Being exploited?UnclearNo reports either way yet
Fix available?YesPython 3.15.1, 3.14.9 and 3.13.17 · since 26 Oct 2026
How sure is this?Official, 2 sourcesBacked by an official source

What happened

Multiple vulnerabilities in CPython (the reference Python interpreter) allow denial of service, file manipulation, information disclosure and security bypass, by remote attackers with or without authentication depending on the flaw.

Why it is dangerous: Servers, scripts and applications running vulnerable Python versions could be crashed, have files altered, or leak sensitive information.

Are you affected?

You are affected if you run CPython 3.13, 3.14 or 3.15 versions older than 3.13.17, 3.14.9 or 3.15.1 respectively.

CPython 3.13.x before 3.13.17; CPython 3.14.x before 3.14.9; CPython 3.15.x before 3.15.1

What to do

  1. Update Python to 3.15.1, 3.14.9 or 3.13.17 (match your current major version)
  2. Rebuild or redeploy applications and containers that bundle Python
  3. Check operating system and vendor packages for updated Python builds

Timeline

  1. 21 Oct 2026, 00:00 UTC
    Publicly disclosed
  2. 25 Oct 2026, 13:32 UTC
    Picked up by Zero Radar
  3. 26 Oct 2026, 07:55 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  4. 26 Oct 2026, 11:44 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  5. 26 Oct 2026, 11:44 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  6. 26 Oct 2026, 11:45 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  7. 26 Oct 2026, 11:45 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  8. 26 Oct 2026, 12:59 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  9. 26 Oct 2026, 13:04 UTC
    Reported by CERT-Bund (BSI) · CERT-Bund (BSI)
  10. 26 Oct 2026, 13:05 UTC
    Python Insider reported on it · Python Insider
  11. 26 Oct 2026, 13:05 UTC
    Fix: Python 3.15.1, 3.14.9 and 3.13.17 (security releases)

Sources 8 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
ZR-eb5074c5 · ZR-000b927b
Disclosed
21 Oct 2026, 00:00 UTC
On Zero Radar
25 Oct 2026, 13:32 UTC (5 days after disclosure)
Last change
26 Oct 2026, 13:10 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Python: several security flaws fixed in new releases · Zero Radar