CVE-2020-28724: Werkzeug Open Redirect Vulnerability

MODERATE
Advisory Identifier: GHSA-3p3h-qghp-hvh2
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CVSS 6.1
CWE-601
Published
Advisory Summary

CVE-2020-28724 is a MODERATE (CVSS 6.1) open redirect vulnerability (CWE-601: URL Redirection to Untrusted Site ('Open Redirect')) affecting Werkzeug libraries in the PyPI ecosystem. The issue involves open redirect in werkzeug. Remediation is available by upgrading affected packages to version 0.11.6.

CVE-2020-28724 at a Glance

CVE Identifier CVE-2020-28724
GHSA Identifier GHSA-3p3h-qghp-hvh2
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-601: URL Redirection to Untrusted Site ('Open Redirect')
Affected Product Werkzeug
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.1

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:R/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 Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2020-28724

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

werkzeug fixed: 0.11.6 
pip install werkzeug>=0.11.6
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 werkzeug

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2020-28724, inspect your installed packages using pip:

pip show werkzeug

Analyze the terminal output to locate any version of Werkzeug in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.11.6), your application is affected.

Note: The pip show werkzeug 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 Werkzeug, 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

Open redirect vulnerability in werkzeug before 0.11.6 via a double slash in the URL.

CVE-2020-28724 Affected Werkzeug Versions

1 component(s)
Fixed Versions:
0.11.6
Product / Package Ecosystem Affected Versions Fixed Version
werkzeug
pypi/werkzeug
PyPI
< 0.11.6
0.11.6

References

NVD — CVE-2020-28724 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-28724
Werkzeug Source Repository REPOSITORY
https://github.com/pallets/flask/issues/1639
Werkzeug Source Repository REPOSITORY
https://github.com/pallets/werkzeug/issues/822
Werkzeug Source Repository REPOSITORY
https://github.com/pallets/werkzeug/pull/890/files
Werkzeug Source Repository REPOSITORY
https://github.com/pallets/werkzeug
Werkzeug Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/werkzeug/PYSEC-2020-157.yaml

Frequently Asked Questions

What is CVE-2020-28724?
CVE-2020-28724 is a security vulnerability in Werkzeug involving Open Redirect in werkzeug under CWE-601: URL Redirection to Untrusted Site ('Open Redirect').
Which Werkzeug versions are affected?
Affected versions include releases prior to 0.11.6 across affected packages: werkzeug.
What version fixes CVE-2020-28724?
Upgrading to 0.11.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is werkzeug affected?
Yes, werkzeug is affected in releases prior to 0.11.6. Upgrade your dependency to 0.11.6 or later.
What is the CVSS score of CVE-2020-28724?
CVE-2020-28724 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2020-28724?
CVE-2020-28724 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-2020-28724?
Run the dependency tree command: 'pip show werkzeug'. 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-3p3h-qghp-hvh2",
  "modified" : "2024-11-19T18:09:23Z",
  "published" : "2021-04-20T16:30:26Z",
  "aliases" : [ "CVE-2020-28724" ],
  "summary" : "Open Redirect in werkzeug",
  "details" : "Open redirect vulnerability in werkzeug before 0.11.6 via a double slash in the URL.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "werkzeug"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.11.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-28724"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pallets/flask/issues/1639"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pallets/werkzeug/issues/822"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pallets/werkzeug/pull/890/files"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/pallets/werkzeug"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/werkzeug/PYSEC-2020-157.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-601" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-15T20:51:30Z",
    "nvd_published_at" : "2020-11-18T15:15:00Z"
  }
}