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Vulnerabilities

Vulnerability · CVE-2025-47278

Flask is a web server gateway interface (WSGI) web application framework.

Published May 13, 2025 · catalog updated May 13, 2025 · Flask

Check if you run it

No confirmed exploitation is on record for CVE-2025-47278. EPSS is 0.19%. Act only if a listed version of Flask is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Low1.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.19%
Remediation
Advisory link
Affected products
vendor pallets Flask = 3.1.0

Flask is a web server gateway interface (WSGI) web application framework. In Flask 3.1.0, the way fallback key configuration was handled resulted in the last fallback key being used for signing, rather than the current signing key. Signing is provided by the library. A list of keys can be passed, and it expects the last (top) key in the list to be the most recent key, and uses that for signing. Flask was incorrectly constructing that list in reverse, passing the signing key first. Sites that have opted-in to use key rotation by setting care likely to unexpectedly be signing their sessions with

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor pallets Flask = 3.1.0= 3.1.0

How to fix CVE-2025-47278

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-47278. EPSS is 0.19%. Act only if a listed version of Flask is installed.

Which versions are affected?

Compare what you have installed with pallets Flask = 3.1.0 = 3.1.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.19%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 13, 2025 · EUVD

    Detected

    Flask is a web server gateway interface (WSGI) web application framework. In Flask 3.1.0, the way fallback key configuration was handled resulted in the last fallback key being used for signing, rather than the current signing key. Signing is provided by the library. A list of keys can be passed, and it expects the last (top) key in the list to be the most recent key, and uses that for signing. Fl

  2. May 13, 2025 · EUVD

    Updated

    Flask is a web server gateway interface (WSGI) web application framework. In Flask 3.1.0, the way fallback key configuration was handled resulted in the last fallback key being used for signing, rather than the current signing key. Signing is provided by the library. A list of keys can be passed, and it expects the last (top) key in the list to be the most recent key, and uses that for signing. Fl

Sources

  • CVE.orgVulnerability recordCVE-2025-47278

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-47278

    30-day exploitation probability 0.2%

    first.org
  • EUVDVulnerability recordEUVD-2025-14386

    Flask is a web server gateway interface (WSGI) web application framework. In Flask 3.1.0, the way fallback key configuration was handled resulted in the last fallback key being used for signing, rather than the current signing key. Signing is provided by the library. A list of ke

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.