CVE-2021-33507: Products.CMFCore Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-35rg-466w-77h3
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2021-33507 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Products.CMFCore libraries in the PyPI ecosystem. The issue involves cross-site scripting in products.cmfcore, products.pluggableauthservice, plone. Remediation is available by upgrading affected packages to version 2.5.1, 2.6.2.

CVE-2021-33507 at a Glance

CVE Identifier CVE-2021-33507
GHSA Identifier GHSA-35rg-466w-77h3
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Products.CMFCore
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-2021-33507

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

Products.CMFCore fixed: 2.5.1 
pip install Products.CMFCore>=2.5.1
Products.PluggableAuthService fixed: 2.6.2 
pip install Products.PluggableAuthService>=2.6.2
Plone fixed: Latest secure release 
pip install Plone>=Latest secure release
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 Products.CMFCore

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-33507, inspect your installed packages using pip:

pip show Products.CMFCore

Analyze the terminal output to locate any version of Products.CMFCore in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.5.1), your application is affected.

Note: The pip show Products.CMFCore command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Products.CMFCore, 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

Zope Products.CMFCore before 2.5.1 and Products.PluggableAuthService before 2.6.2, as used in Plone through 5.2.4 and other products, allow Reflected XSS.

CVE-2021-33507 Affected Products.CMFCore Versions

3 component(s)
Fixed Versions:
2.5.12.6.2
Product / Package Ecosystem Affected Versions Fixed Version
Products.CMFCore
pypi/Products.CMFCore
PyPI
< 2.5.1
2.5.1
Products.PluggableAuthService
pypi/Products.PluggableAuthService
PyPI
< 2.6.2
2.6.2
Plone
pypi/Plone
PyPI
≤ 5.2.4

References

NVD — CVE-2021-33507 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-33507
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-35rg-466w-77h3
Products.CMFCore Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/plone/PYSEC-2021-79.yaml
Products.CMFCore Security Information SECURITY
https://plone.org/security/hotfix/20210518/reflected-xss-in-various-spots
Products.CMFCore Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/05/22/1

Frequently Asked Questions

What is CVE-2021-33507?
CVE-2021-33507 is a security vulnerability in Products.CMFCore involving Cross-site scripting in Products.CMFCore, Products.PluggableAuthService, Plone under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Products.CMFCore versions are affected?
Affected versions include releases prior to 2.5.1, 2.6.2 across affected packages: Products.CMFCore, Products.PluggableAuthService, Plone.
What version fixes CVE-2021-33507?
Upgrading to 2.5.1, 2.6.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Products.CMFCore affected?
Yes, Products.CMFCore is affected in releases prior to 2.5.1. Upgrade your dependency to 2.5.1 or later.
Is Products.PluggableAuthService affected?
Yes, Products.PluggableAuthService is affected in releases prior to 2.6.2. Upgrade your dependency to 2.6.2 or later.
What is the CVSS score of CVE-2021-33507?
CVE-2021-33507 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-2021-33507?
CVE-2021-33507 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check PyPI dependencies for CVE-2021-33507?
Run the dependency tree command: 'pip show Products.CMFCore'. 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-35rg-466w-77h3",
  "modified" : "2024-10-18T21:50:41Z",
  "published" : "2021-06-18T18:44:50Z",
  "aliases" : [ "CVE-2021-33507" ],
  "summary" : "Cross-site scripting in Products.CMFCore, Products.PluggableAuthService, Plone",
  "details" : "Zope Products.CMFCore before 2.5.1 and Products.PluggableAuthService before 2.6.2, as used in Plone through 5.2.4 and other products, allow Reflected XSS.",
  "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" : "Products.CMFCore"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.5.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Products.PluggableAuthService"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.6.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Plone"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "5.2.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-33507"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-35rg-466w-77h3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/plone/PYSEC-2021-79.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://plone.org/security/hotfix/20210518/reflected-xss-in-various-spots"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/05/22/1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-27T21:54:47Z",
    "nvd_published_at" : "2021-05-21T22:15:00Z"
  }
}