CVE-2020-13940: Nifi Improper Restriction Of XML External Vulnerability

MODERATE
Advisory Identifier: GHSA-q4xf-3pmq-3hw8
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CVSS 5.5
CWE-611
Published
Advisory Summary

CVE-2020-13940 is a MODERATE (CVSS 5.5) improper restriction of xml external vulnerability (CWE-611: Improper Restriction of XML External Entity Reference) affecting Nifi libraries in the Maven ecosystem. The issue involves improper restriction of xml external entity reference in apache nifi. Remediation is available by upgrading affected packages to version 1.12.0-RC1.

CVE-2020-13940 at a Glance

CVE Identifier CVE-2020-13940
GHSA Identifier GHSA-q4xf-3pmq-3hw8
Severity MODERATE
CVSS v3.1 Base Score 5.5
CWE Classification CWE-611: Improper Restriction of XML External Entity Reference
Affected Product Nifi
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.5

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

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

How to Fix CVE-2020-13940

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

org.apache.nifi:nifi fixed: 1.12.0-RC1 
<dependency>
    <groupId>org.apache.nifi</groupId>
    <artifactId>nifi</artifactId>
    <version>1.12.0-RC1</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.apache.nifi

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2020-13940, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.apache.nifi

Analyze the terminal output to locate any version of Nifi in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.12.0-RC1), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.apache.nifi command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

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 Nifi, 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

In Apache NiFi 1.0.0 to 1.11.4, the notification service manager and various policy authorizer and user group provider objects allowed trusted administrators to inadvertently configure a potentially malicious XML file. The XML file has the ability to make external calls to services (via XXE).

CVE-2020-13940 Affected Nifi Versions

1 component(s)
Fixed Versions:
1.12.0-RC1
Product / Package Ecosystem Affected Versions Fixed Version
org.apache.nifi:nifi
maven/org.apache.nifi/nifi
Maven
≥ 1.0.0
< 1.12.0-RC1
1.12.0-RC1

References

NVD — CVE-2020-13940 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-13940
Security Fix Commit FIX COMMIT
https://github.com/apache/nifi/commit/7f0416ee8bdcee95e28409cc6fae9c1394c2a798
Nifi Security Information SECURITY
https://nifi.apache.org/security#CVE-2020-13940

Frequently Asked Questions

What is CVE-2020-13940?
CVE-2020-13940 is a security vulnerability in Nifi involving Improper Restriction of XML External Entity Reference in Apache NiFi under CWE-611: Improper Restriction of XML External Entity Reference.
Which Nifi versions are affected?
Affected versions include releases prior to 1.12.0-RC1 across affected packages: org.apache.nifi:nifi.
What version fixes CVE-2020-13940?
Upgrading to 1.12.0-RC1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is nifi affected?
Yes, org.apache.nifi:nifi is affected in releases prior to 1.12.0-RC1. Upgrade your dependency to 1.12.0-RC1 or later.
What is the CVSS score of CVE-2020-13940?
CVE-2020-13940 has a CVSS v3.1 base score of 5.5 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2020-13940?
CVE-2020-13940 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 Maven dependencies for CVE-2020-13940?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.apache.nifi'. 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-q4xf-3pmq-3hw8",
  "modified" : "2021-03-29T16:20:14Z",
  "published" : "2022-01-06T20:41:00Z",
  "aliases" : [ "CVE-2020-13940" ],
  "summary" : "Improper Restriction of XML External Entity Reference in Apache NiFi",
  "details" : "In Apache NiFi 1.0.0 to 1.11.4, the notification service manager and various policy authorizer and user group provider objects allowed trusted administrators to inadvertently configure a potentially malicious XML file. The XML file has the ability to make external calls to services (via XXE).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.apache.nifi:nifi"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.0"
      }, {
        "fixed" : "1.12.0-RC1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.11.4"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-13940"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apache/nifi/commit/7f0416ee8bdcee95e28409cc6fae9c1394c2a798"
  }, {
    "type" : "WEB",
    "url" : "https://nifi.apache.org/security#CVE-2020-13940"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-611" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-03-29T16:20:14Z",
    "nvd_published_at" : "2020-10-01T20:15:00Z"
  }
}