CVE-2020-26709: Py xml Py-xml XML External Entity Injection Vulnerability

HIGH
Advisory Identifier: GHSA-j6v2-mwxm-f952
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CVSS 7.5
CWE-611
Published
Advisory Summary

CVE-2020-26709 is a HIGH (CVSS 7.5) py-xml xml external entity injection vulnerability (CWE-611: Improper Restriction of XML External Entity Reference) affecting Py xml libraries in the PyPI ecosystem. The issue involves py-xml xml external entity injection vulnerability. Remediation is available in the latest vendor maintenance releases.

CVE-2020-26709 at a Glance

CVE Identifier CVE-2020-26709
GHSA Identifier GHSA-j6v2-mwxm-f952
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-611: Improper Restriction of XML External Entity Reference
Affected Product Py xml
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:N/I:N/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 None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2020-26709

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

py-xml fixed: Latest secure release 
pip install py-xml>=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 py-xml

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2020-26709, inspect your installed packages using pip:

pip show py-xml

Analyze the terminal output to locate any version of Py xml 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 py-xml 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 Py xml, 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

py-xml v1.0 was discovered to contain an XML External Entity Injection (XXE) vulnerability which allows attackers to execute arbitrary code via a crafted XML file.

CVE-2020-26709 Affected Py xml Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
py-xml
pypi/py-xml
PyPI
≤ 1.0

References

NVD — CVE-2020-26709 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-26709
Py xml Source Repository REPOSITORY
https://github.com/PinaeOS/py-xml/issues/2
Py xml Source Repository REPOSITORY
https://github.com/PinaeOS/py-xml
Py xml Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/py-xml/PYSEC-2023-95.yaml

Frequently Asked Questions

What is CVE-2020-26709?
CVE-2020-26709 is a security vulnerability in Py xml involving py-xml XML External Entity Injection vulnerability under CWE-611: Improper Restriction of XML External Entity Reference.
Which Py xml versions are affected?
Affected versions include releases prior to current release patches across affected packages: py-xml.
What version fixes CVE-2020-26709?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is py-xml affected?
Yes, py-xml 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-2020-26709?
CVE-2020-26709 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2020-26709?
CVE-2020-26709 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-2020-26709?
Run the dependency tree command: 'pip show py-xml'. 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-j6v2-mwxm-f952",
  "modified" : "2023-07-06T21:39:34Z",
  "published" : "2023-06-29T21:30:29Z",
  "aliases" : [ "CVE-2020-26709" ],
  "summary" : "py-xml XML External Entity Injection vulnerability",
  "details" : "py-xml v1.0 was discovered to contain an XML External Entity Injection (XXE) vulnerability which allows attackers to execute arbitrary code via a crafted XML file.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "py-xml"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "1.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-26709"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/PinaeOS/py-xml/issues/2"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/PinaeOS/py-xml"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/py-xml/PYSEC-2023-95.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-611" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-06-30T20:36:36Z",
    "nvd_published_at" : "2023-06-29T21:15:09Z"
  }
}