CVE-2025-47278

1.8 LOW 0.2% exploit odds Fix listed Other Web app

What it is

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 `itsdangerous` 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 `SECRET_KEY_FALLBACKS` care likely to unexpectedly be signing their sessions with stale keys, and their transition to fresher keys will be impeded. Sessions are still signed, so this would not cause any sort of data integrity loss. Version 3.1.1 contains a patch for the issue.

At a glance

Exploitability: Can be exploited locally on the machine with an admin-level account. Limited direct impact.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-05-13 16:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 09:27 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 1.8 LOW (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2025-05-13 16:15 UTC
Last modified: 2026-06-17 09:27 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-683
Record status: Deferred

Attack profile CVSS 4.0 · 1.8

Attack vector: Local
Complexity: Low
Attack requirements: Present
Privileges needed: High
User interaction: None
Confidentiality: None
Integrity: None
Availability: Low

Raw vector

CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2025-47278.md and follow it. Check whether this project is affected by CVE-2025-47278. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record