CVE-2025-47278: PYSEC-2026-1377 - Flask uses fallback key instead of current signing key

CVE-2025-47278 · Severity: medium · CVSS 4 · Published 2026-07-07

Flask uses fallback key instead of current signing key

Technologies: flask (PyPI). Vendors: PyPI.

Quick answers

Is CVE-2025-47278 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2025-47278 being exploited in the wild.
How severe is CVE-2025-47278?
Medium severity, with a CVSS score of 4, published 7 July 2026.
Which products and versions are affected?
flask (PyPI) ECOSYSTEM:introduced=3.1.0,fixed=3.1.1.
Is there a fix for CVE-2025-47278?
Yes. flask (PyPI): upgrade to 3.1.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2025-47278?
Check whether you run flask (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • flask (PyPI): upgrade to 3.1.1 or later
    pip install "flask>=3.1.1"

Affected products

  • flask (PyPI) ECOSYSTEM:introduced=3.1.0,fixed=3.1.1

Identifiers

  • CVE-2025-47278
  • GHSA-4grg-w6v8-c28g
  • PYSEC-2026-1377

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