CVE-2020-28735: Plone SSRF Attacks Vulnerability

HIGH
Advisory Identifier: GHSA-x7wf-5mjc-6x76
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CVSS 8.8
CWE-918
Published
Advisory Summary

CVE-2020-28735 is a HIGH (CVSS 8.8) ssrf attacks vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Plone libraries in the PyPI ecosystem. The issue involves ssrf attacks via tracebacks in plone. Remediation is available by upgrading affected packages to version 5.2.3, 3.2.10, 4.1.6, 2.6.8, 1.6.3.

CVE-2020-28735 at a Glance

CVE Identifier CVE-2020-28735
GHSA Identifier GHSA-x7wf-5mjc-6x76
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-918: Server-Side Request Forgery (SSRF)
Affected Product Plone
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 8.8

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

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

How to Fix CVE-2020-28735

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

Plone fixed: 5.2.3 
pip install Plone>=5.2.3
plone.app.event fixed: 3.2.10 
pip install plone.app.event>=3.2.10
plone.app.theming fixed: 4.1.6 
pip install plone.app.theming>=4.1.6
plone.app.dexterity fixed: 2.6.8 
pip install plone.app.dexterity>=2.6.8
plone.supermodel fixed: 1.6.3 
pip install plone.supermodel>=1.6.3
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 Plone

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2020-28735, inspect your installed packages using pip:

pip show Plone

Analyze the terminal output to locate any version of Plone in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.2.3), your application is affected.

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. In Plone, 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

Plone before 5.2.3 allows SSRF attacks via the tracebacks feature (only available to the Manager role).

CVE-2020-28735 Affected Plone Versions

5 component(s)
Fixed Versions:
5.2.33.2.104.1.62.6.81.6.3
Product / Package Ecosystem Affected Versions Fixed Version
Plone
pypi/Plone
PyPI
< 5.2.3
5.2.3
plone.app.event
pypi/plone.app.event
PyPI
< 3.2.10
3.2.10
plone.app.theming
pypi/plone.app.theming
PyPI
< 4.1.6
4.1.6
plone.app.dexterity
pypi/plone.app.dexterity
PyPI
< 2.6.8
2.6.8
plone.supermodel
pypi/plone.supermodel
PyPI
< 1.6.3
1.6.3

References

NVD — CVE-2020-28735 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-28735
Plone Source Repository REPOSITORY
https://github.com/plone/Products.CMFPlone/issues/3209
Plone Release RELEASE
https://dist.plone.org/release/5.2.3/RELEASE-NOTES.txt
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-x7wf-5mjc-6x76
Plone Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/plone/PYSEC-2020-247.yaml
www.misakikata.com/codes/plone/python-... WEB
https://www.misakikata.com/codes/plone/python-en.html

Frequently Asked Questions

What is CVE-2020-28735?
CVE-2020-28735 is a security vulnerability in Plone involving SSRF attacks via tracebacks in Plone under CWE-918: Server-Side Request Forgery (SSRF).
Which Plone versions are affected?
Affected versions include releases prior to 5.2.3, 3.2.10, 4.1.6, 2.6.8, 1.6.3 across affected packages: Plone, plone.app.event, plone.app.theming, plone.app.dexterity, plone.supermodel.
What version fixes CVE-2020-28735?
Upgrading to 5.2.3, 3.2.10, 4.1.6, 2.6.8, 1.6.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Plone affected?
Yes, Plone is affected in releases prior to 5.2.3. Upgrade your dependency to 5.2.3 or later.
Is plone.app.event affected?
Yes, plone.app.event is affected in releases prior to 3.2.10. Upgrade your dependency to 3.2.10 or later.
What is the CVSS score of CVE-2020-28735?
CVE-2020-28735 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2020-28735?
CVE-2020-28735 is classified under CWE-918: Server-Side Request Forgery (SSRF) (The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.).
How can I check PyPI dependencies for CVE-2020-28735?
Run the dependency tree command: 'pip show Plone'. 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-x7wf-5mjc-6x76",
  "modified" : "2024-10-15T20:03:06Z",
  "published" : "2021-04-07T21:13:44Z",
  "aliases" : [ "CVE-2020-28735" ],
  "summary" : "SSRF attacks via tracebacks in Plone",
  "details" : "Plone before 5.2.3 allows SSRF attacks via the tracebacks feature (only available to the Manager role).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "Plone"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.2.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "plone.app.event"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.2.10"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "plone.app.theming"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.6"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "plone.app.dexterity"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.6.8"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "plone.supermodel"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.6.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-28735"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/plone/Products.CMFPlone/issues/3209"
  }, {
    "type" : "WEB",
    "url" : "https://dist.plone.org/release/5.2.3/RELEASE-NOTES.txt"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-x7wf-5mjc-6x76"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/plone/PYSEC-2020-247.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://www.misakikata.com/codes/plone/python-en.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-07T19:31:51Z",
    "nvd_published_at" : "2020-12-30T19:15:00Z"
  }
}