Sonatype Nexus Repository Manager 3 Java Expression Language (EL) Injection Remote Code Execution Vulnerability (CVE-2020-10199) Analysis and Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTSonatype Nexus Repository Manager versions prior to 3.21.2
An authenticated attacker with low privileges can execute arbitrary system commands on the server by sending a specially crafted request.
Immediately upgrade Nexus Repository Manager to the latest stable version (3.21.2 or higher).
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to upgrade Nexus Repository Manager to version 3.21.2 or later. For Docker-based deployments, use the following commands to pull and run the patched version:
# Upgrade Nexus 3 in Docker environment
docker pull sonatype/nexus3:3.21.2
docker stop nexus-container
docker run -d -p 8081:8081 --name nexus-new -v nexus-data:/nexus-data sonatype/nexus3:3.21.22. Temporary Workaround & Hardening Configuration
If an immediate upgrade is not feasible, restrict access to the Nexus API and web interface using a reverse proxy or firewall. Below is an Nginx configuration snippet to restrict access to sensitive API paths:
# Restricting API access via Nginx reverse proxy
server {
listen 80;
server_name nexus.internal.local;
location /service/rest/ {
allow 10.0.0.0/8; # Allow trusted internal network only
deny all;
proxy_pass http://localhost:8081;
}
}3. Log Audit & IoC Verification Commands
Run the following command to inspect the Nexus request.log for potential Java EL injection attempts containing suspicious keywords:
# Search for malicious Java EL patterns in Nexus request logs
grep -Ei '\$\{.*(runtime|processbuilder|classloader|getmethod).*\}' /opt/sonatype/sonatype-work/nexus3/log/request.logScan Your Repositories for Transitive Vulnerable Dependencies in 30 Seconds
Automatically detect vulnerable packages across npm, PyPI, Maven, and Go, and open automated fix Pull Requests without breaking your build.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2020-10199) is a Java Expression Language (EL) injection flaw in Sonatype Nexus Repository Manager 3. The root cause lies in the application's failure to properly validate and sanitize user-controlled input before passing it to the Java EL evaluation engine. This allows an attacker to inject and execute arbitrary Java code within the application context.
2. Exploitation Mechanics & Attack Scenario
An attacker with a valid user account (even with minimal privileges) can submit malicious payloads containing Java EL syntax (e.g., ${...}) through specific API endpoints or configuration parameters. When the server-side validation or rendering engine processes this input without proper escaping, it evaluates the expression, allowing the attacker to instantiate arbitrary Java classes and execute system-level commands.
3. Infrastructure & Business Impact
Nexus Repository Manager serves as a critical asset in DevSecOps pipelines, hosting proprietary software artifacts and dependencies. Successful exploitation of this vulnerability could allow attackers to compromise the build pipeline, inject malicious code into software artifacts (Supply Chain Attack), or exfiltrate sensitive source code. Since this vulnerability is actively exploited in the wild (CISA KEV), immediate remediation is critical.
Official Vendor Advisories & References
Sonatype Nexus Repository before 3.21.2 allows JavaEL Injection (issue 1 of 2).
Frequently Asked SecOps Questions (CVE-2020-10199)
FAQQ1. How critical is CVE-2020-10199 and is it actively exploited in the wild?
CVE-2020-10199 is rated CVSS 8.8 (HIGH) with a 30-day EPSS exploitation probability of 99.1%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2020-10199?
Primary impacted vendors include sonatype across nexus repository manager. Scope summary: Sonatype Nexus Repository Manager 3 versions prior to 3.21.2 (3.21.1-01 and earlier)
Q3. What temporary mitigations or workarounds exist for CVE-2020-10199 before patching?
[Mitigation] Immediately upgrade Nexus Repository Manager to the latest stable version (3.21.2 or higher). Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2020-10199
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
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