CVE-2020-18703: Quokka Improper Restriction Of XML External Vulnerability

CRITICAL
Advisory Identifier: GHSA-3xg5-6c3j-vp8x
Share
CVSS 9.8
CWE-611
Published
Advisory Summary

CVE-2020-18703 is a CRITICAL (CVSS 9.8) improper restriction of xml external vulnerability (CWE-611: Improper Restriction of XML External Entity Reference) affecting Quokka libraries in the PyPI ecosystem. The issue involves improper restriction of xml external entity reference in quokka. Remediation is available in the latest vendor maintenance releases.

CVE-2020-18703 at a Glance

CVE Identifier CVE-2020-18703
GHSA Identifier GHSA-3xg5-6c3j-vp8x
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-611: Improper Restriction of XML External Entity Reference
Affected Product Quokka
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 9.8

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:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
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-2020-18703

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

quokka fixed: Latest secure release 
pip install quokka>=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 quokka

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2020-18703, inspect your installed packages using pip:

pip show quokka

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

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-611: Improper Restriction of XML External Entity Reference, where the product processes an xml document that can contain xml entities with uris that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output. In Quokka, 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

XML External Entities (XXE) in Quokka v0.4.0 allows remote attackers to execute arbitrary code via the component 'quokka/utils/atom.py'.

CVE-2020-18703 Affected Quokka Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
quokka
pypi/quokka
PyPI
≤ 0.4.0

References

NVD — CVE-2020-18703 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-18703
Quokka Source Repository REPOSITORY
https://github.com/rochacbruno/quokka/issues/676
Quokka Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/quokka/PYSEC-2021-144.yaml
Quokka Source Repository REPOSITORY
https://github.com/quokkaproject/quokka

Frequently Asked Questions

What is CVE-2020-18703?
CVE-2020-18703 is a security vulnerability in Quokka involving Improper Restriction of XML External Entity Reference in Quokka under CWE-611: Improper Restriction of XML External Entity Reference.
Which Quokka versions are affected?
Affected versions include releases prior to current release patches across affected packages: quokka.
What version fixes CVE-2020-18703?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is quokka affected?
Yes, quokka is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2020-18703?
CVE-2020-18703 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2020-18703?
CVE-2020-18703 is classified under CWE-611: Improper Restriction of XML External Entity Reference (The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.).
How can I check PyPI dependencies for CVE-2020-18703?
Run the dependency tree command: 'pip show quokka'. 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-3xg5-6c3j-vp8x",
  "modified" : "2024-10-16T21:28:22Z",
  "published" : "2021-08-30T16:23:34Z",
  "aliases" : [ "CVE-2020-18703" ],
  "summary" : "Improper Restriction of XML External Entity Reference in Quokka",
  "details" : "XML External Entities (XXE) in Quokka v0.4.0 allows remote attackers to execute arbitrary code via the component 'quokka/utils/atom.py'.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "quokka"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.4.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-18703"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rochacbruno/quokka/issues/676"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/quokka/PYSEC-2021-144.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/quokkaproject/quokka"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-611" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-26T17:42:07Z",
    "nvd_published_at" : "2021-08-16T18:15:00Z"
  }
}