GHSA-4GRG-W6V8-C28G

Vulnerability from github – Published: 2025-05-13 20:25 – Updated: 2025-05-13 20:25
VLAI?
Summary
Flask uses fallback key instead of current signing key
Details

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 are 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.

Severity ?
1.8 (Low)
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
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "flask"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.1.0"
            },
            {
              "fixed": "3.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.1.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2025-47278"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-683"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-05-13T20:25:26Z",
    "nvd_published_at": "2025-05-13T16:15:32Z",
    "severity": "LOW"
  },
  "details": "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.\n\nSigning 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.\n\nSites that have opted-in to use key rotation by setting `SECRET_KEY_FALLBACKS` are 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.",
  "id": "GHSA-4grg-w6v8-c28g",
  "modified": "2025-05-13T20:25:26Z",
  "published": "2025-05-13T20:25:26Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pallets/flask/security/advisories/GHSA-4grg-w6v8-c28g"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-47278"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pallets/flask/commit/73d6504063bfa00666a92b07a28aaf906c532f09"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pallets/flask"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pallets/flask/releases/tag/3.1.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Flask uses fallback key instead of current signing key"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.