CVE-2021-32805: Flask AppBuilder Flask-AppBuilder Open Redirect Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-624f-cqvr-3qw4
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CVSS 7.2
CWE-601
Published
Advisory Summary

CVE-2021-32805 is a MODERATE (CVSS 7.2) flask-appbuilder open redirect vulnerability vulnerability (CWE-601: URL Redirection to Untrusted Site ('Open Redirect')) affecting Flask AppBuilder libraries in the PyPI ecosystem. The issue involves flask-appbuilder open redirect vulnerability. Remediation is available by upgrading affected packages to version 3.3.2.

CVE-2021-32805 at a Glance

CVE Identifier CVE-2021-32805
GHSA Identifier GHSA-624f-cqvr-3qw4
Severity MODERATE
CVSS v3.1 Base Score 7.2
CWE Classification CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
Affected Product Flask AppBuilder
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-32805

To remediate this vulnerability, upgrade all affected Flask AppBuilder dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Flask-AppBuilder fixed: 3.3.2 
pip install Flask-AppBuilder>=3.3.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show Flask-AppBuilder

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-32805, inspect your installed packages using pip:

pip show Flask-AppBuilder

Analyze the terminal output to locate any version of Flask AppBuilder in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.3.2), your application is affected.

Note: The pip show Flask-AppBuilder command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-601: URL Redirection to Untrusted Site ('Open Redirect'), where the web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect. In Flask AppBuilder, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact If using Flask-AppBuilder OAuth, an attacker can share a carefully crafted URL with a trusted domain for an application built with Flask-AppBuilder, this URL can redirect a user to a malicious site. This is an open redirect vulnerability ### Patches Install Flask-AppBuilder 3.2.2 or above ### Workarounds Filter HTTP traffic containing `?next={next-site}` where the `next-site` domain is different from the application you are protecting

CVE-2021-32805 Affected Flask AppBuilder Versions

1 component(s)
Fixed Versions:
3.3.2
Product / Package Ecosystem Affected Versions Fixed Version
Flask-AppBuilder
pypi/Flask-AppBuilder
PyPI
< 3.3.2
3.3.2

References

Flask AppBuilder Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/flask-appbuilder/PYSEC-2021-359.yaml
pypi.org/project/flask-appbu... WEB
https://pypi.org/project/Flask-AppBuilder
GitHub Advisory / Wiki ADVISORY
https://github.com/dpgaspar/Flask-AppBuilder/security/advisories/GHSA-624f-cqvr-3qw4
NVD — CVE-2021-32805 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-32805
Security Fix Commit FIX COMMIT
https://github.com/dpgaspar/Flask-AppBuilder/commit/6af28521589599b1dbafd6313256229ee9a4fa74
Flask AppBuilder Source Repository REPOSITORY
https://github.com/dpgaspar/Flask-AppBuilder
Flask AppBuilder Release RELEASE
https://github.com/dpgaspar/Flask-AppBuilder/releases/tag/v3.3.2

Frequently Asked Questions

What is CVE-2021-32805?
CVE-2021-32805 is a security vulnerability in Flask AppBuilder involving Flask-AppBuilder Open Redirect vulnerability under CWE-601: URL Redirection to Untrusted Site ('Open Redirect').
Which Flask AppBuilder versions are affected?
Affected versions include releases prior to 3.3.2 across affected packages: Flask-AppBuilder.
What version fixes CVE-2021-32805?
Upgrading to 3.3.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Flask-AppBuilder affected?
Yes, Flask-AppBuilder is affected in releases prior to 3.3.2. Upgrade your dependency to 3.3.2 or later.
What is the CVSS score of CVE-2021-32805?
CVE-2021-32805 has a CVSS v3.1 base score of 7.2 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-32805?
CVE-2021-32805 is classified under CWE-601: URL Redirection to Untrusted Site ('Open Redirect') (The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.).
How can I check PyPI dependencies for CVE-2021-32805?
Run the dependency tree command: 'pip show Flask-AppBuilder'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-624f-cqvr-3qw4",
  "modified" : "2025-03-07T19:09:11Z",
  "published" : "2021-09-08T21:11:14Z",
  "aliases" : [ "CVE-2021-32805" ],
  "summary" : "Flask-AppBuilder Open Redirect vulnerability",
  "details" : "### Impact\nIf using Flask-AppBuilder OAuth, an attacker can share a carefully crafted URL with a trusted domain for an application built with Flask-AppBuilder, this URL can redirect a user to a malicious site. This is an open redirect vulnerability \n\n### Patches\nInstall Flask-AppBuilder 3.2.2 or above\n\n### Workarounds\nFilter HTTP traffic containing `?next={next-site}` where the `next-site` domain is different from the application you are protecting",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Flask-AppBuilder"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.3.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/dpgaspar/Flask-AppBuilder/security/advisories/GHSA-624f-cqvr-3qw4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-32805"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/dpgaspar/Flask-AppBuilder/commit/6af28521589599b1dbafd6313256229ee9a4fa74"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/dpgaspar/Flask-AppBuilder"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/dpgaspar/Flask-AppBuilder/releases/tag/v3.3.2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/flask-appbuilder/PYSEC-2021-359.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://pypi.org/project/Flask-AppBuilder"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-601" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-09-08T21:10:56Z",
    "nvd_published_at" : "2021-09-08T18:15:00Z"
  }
}