CVE-2020-9296: Conductor core Expression Language Injection Vulnerability

CRITICAL
Advisory Identifier: GHSA-wfj5-2mqr-7jvv
Share
CVSS 9.8
CWE-917
Published
Advisory Summary

CVE-2020-9296 is a CRITICAL (CVSS 9.8) expression language injection vulnerability (CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')) affecting Conductor core libraries in the Maven ecosystem. The issue involves expression language injection in netflix conductor. Remediation is available by upgrading affected packages to version 2.25.4.

CVE-2020-9296 at a Glance

CVE Identifier CVE-2020-9296
GHSA Identifier GHSA-wfj5-2mqr-7jvv
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
Affected Product Conductor core
Package Ecosystem Maven
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-2020-9296

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

com.netflix.conductor:conductor-core fixed: 2.25.4 
<dependency>
    <groupId>com.netflix.conductor</groupId>
    <artifactId>conductor-core</artifactId>
    <version>2.25.4</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=com.netflix.conductor

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2020-9296, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=com.netflix.conductor

Analyze the terminal output to locate any version of Conductor core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.25.4), your application is affected.

Note: The mvn dependency:tree -Dincludes=com.netflix.conductor 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-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection'), where the product constructs all or part of an expression language (el) statement in a framework such as a java server page (jsp) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended el statement before it is executed. In Conductor core, 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

Netflix Conductor uses Java Bean Validation (JSR 380) custom constraint validators. When building custom constraint violation error messages, different types of interpolation are supported, including Java EL expressions. If an attacker can inject arbitrary data in the error message template being passed to ConstraintValidatorContext.buildConstraintViolationWithTemplate() argument, they will be able to run arbitrary Java code.

CVE-2020-9296 Affected Conductor core Versions

1 component(s)
Fixed Versions:
2.25.4
Product / Package Ecosystem Affected Versions Fixed Version
com.netflix.conductor:conductor-core
maven/com.netflix.conductor/conductor-core
Maven
< 2.25.4
2.25.4

References

NVD — CVE-2020-9296 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-9296
GitHub Advisory / Wiki ADVISORY
https://github.com/Netflix/security-bulletins/blob/master/advisories/nflx-2020-001.md
GitHub Advisory / Wiki ADVISORY
https://github.com/Netflix/security-bulletins/blob/master/advisories/nflx-2020-002.md

Frequently Asked Questions

What is CVE-2020-9296?
CVE-2020-9296 is a security vulnerability in Conductor core involving Expression Language Injection in Netflix Conductor under CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection').
Which Conductor core versions are affected?
Affected versions include releases prior to 2.25.4 across affected packages: com.netflix.conductor:conductor-core.
What version fixes CVE-2020-9296?
Upgrading to 2.25.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is conductor-core affected?
Yes, com.netflix.conductor:conductor-core is affected in releases prior to 2.25.4. Upgrade your dependency to 2.25.4 or later.
What is the CVSS score of CVE-2020-9296?
CVE-2020-9296 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-2020-9296?
CVE-2020-9296 is classified under CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection') (The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.).
How can I check Maven dependencies for CVE-2020-9296?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=com.netflix.conductor'. 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-wfj5-2mqr-7jvv",
  "modified" : "2021-07-29T18:20:14Z",
  "published" : "2022-02-10T23:06:57Z",
  "aliases" : [ "CVE-2020-9296" ],
  "summary" : "Expression Language Injection in Netflix Conductor",
  "details" : "Netflix Conductor uses Java Bean Validation (JSR 380) custom constraint validators. When building custom constraint violation error messages, different types of interpolation are supported, including Java EL expressions. If an attacker can inject arbitrary data in the error message template being passed to ConstraintValidatorContext.buildConstraintViolationWithTemplate() argument, they will be able to run arbitrary Java code.",
  "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" : "Maven",
      "name" : "com.netflix.conductor:conductor-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.25.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.25.3"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-9296"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Netflix/security-bulletins/blob/master/advisories/nflx-2020-001.md"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Netflix/security-bulletins/blob/master/advisories/nflx-2020-002.md"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-917" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-12T14:18:14Z",
    "nvd_published_at" : "2020-06-16T14:15:00Z"
  }
}