CVE catalog

CVE-2025-47278

flask: CVE-2025-47278

Severity: Low · CVSS 2.3CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
Published: May 13, 2025, 3:57:40 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.19% · Oct 25, 2026

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.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	flask	sid	`3.1.3-4`	fixed
Debian	flask	forky	`3.1.3-4`	fixed
Debian	flask	trixie	`3.1.1-1+deb13u1`	fixed
Debian	flask	bookworm	`2.2.2-3`	not affected
Opensuse	python-Flask	tumbleweed	`3.1.1-1.1`	fixed
Ubuntu	flask	25.04	`3.0.3-1ubuntu1`	vulnerable
Ubuntu	flask	25.04	`3.1.0-2ubuntu1`	vulnerable
Ubuntu	flask	25.04	`3.1.0-2ubuntu1.1`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	flask	source	sid	`3.1.1-1`	not yet assigned	Not reported	[1105794]
Debian	flask	source	forky	`3.1.1-1`	not yet assigned	Not reported	[1105794]
Debian	flask	source	trixie	`3.1.1-1`	not yet assigned	Not reported	[1105794]
Debian	flask	source	bookworm	`Not affected`	unimportant	Not reported	[1105794]
Opensuse	python-Flask	rpm	tumbleweed	`3.1.1-1.1`	Not reported	OPENSUSE-SU-2025:15152-1	Not reported
Ubuntu	flask	deb	25.04	`3.1.0-2ubuntu1.1`	Not reported	USN-7534-1	Not reported

[Debian bug #1105794]

OpenFactory catalog packages

[openSUSE Tumbleweed]

[python313-Flask]Unknown
Source package: [python-Flask]
Details (1)
- 3.1.3-2.2 · noarch · tumbleweed
  Unknown · Fixed: 3.1.1-1.1
  Version impact unknown
  dsa · python-Flask · opensuse · tumbleweed
[python313-Flask-doc]Unknown
Source package: [python-Flask]
Details (1)
- 3.1.3-2.2 · noarch · tumbleweed
  Unknown · Fixed: 3.1.1-1.1
  Version impact unknown
  dsa · python-Flask · opensuse · tumbleweed
[python314-Flask]Unknown
Source package: [python-Flask]
Details (1)
- 3.1.3-2.2 · noarch · tumbleweed
  Unknown · Fixed: 3.1.1-1.1
  Version impact unknown
  dsa · python-Flask · opensuse · tumbleweed
[python314-Flask-doc]Unknown
Source package: [python-Flask]
Details (1)
- 3.1.3-2.2 · noarch · tumbleweed
  Unknown · Fixed: 3.1.1-1.1
  Version impact unknown
  dsa · python-Flask · opensuse · tumbleweed

[Debian 12 (Bookworm)]

[python3-flask]Not affected
Source package: [flask]
Details (2)
- 2.2.2-3 · all · bookworm
  Not affected
  dsa · flask · debian · bookworm
- 2.2.2-3 · all · bookworm
  Not affected
  dsa · flask · debian · bookworm
[python-flask-doc]Not affected
Source package: [flask]
Details (2)
- 2.2.2-3 · all · bookworm
  Not affected
  dsa · flask · debian · bookworm
- 2.2.2-3 · all · bookworm
  Not affected
  dsa · flask · debian · bookworm

[Debian 13 (Trixie)]

[python3-flask]Fixed
Source package: [flask]
Details (2)
- 3.1.1-1 · all · trixie
  Fixed · Fixed: 3.1.1-1
  dsa · flask · debian · 13
- 3.1.1-1 · all · trixie
  Fixed · Fixed: 3.1.1-1
  dsa · flask · debian · 13
[python-flask-doc]Fixed
Source package: [flask]
Details (2)
- 3.1.1-1 · all · trixie
  Fixed · Fixed: 3.1.1-1
  dsa · flask · debian · 13
- 3.1.1-1 · all · trixie
  Fixed · Fixed: 3.1.1-1
  dsa · flask · debian · 13

Observed: Oct 24, 2026, 10:21:51 PM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]