CVE-2020-10199: Sonatype Nexus Repository Remote Code Execution Vulnerability

CVE-2020-10199 is a remote code execution vulnerability in Sonatype Nexus Repository. CISA describes it as an unspecified flaw that lets an attacker run code on the affected system. For teams that rely on Nexus to host and distribute artifacts, successful exploitation can give an attacker control over the repository host and the software supply chain it serves. Confirm exact impact, versions, and fixes against the vendor advisory.

How it works

The weakness is tracked as CWE-917 (expression language injection). In products of this class, user-controlled input is evaluated by an expression language engine without proper sanitization or sandboxing. An attacker who can reach the vulnerable interface supplies crafted input that the engine interprets as code rather than data. That evaluation can lead to arbitrary command execution in the context of the Nexus process. Public detail on the precise injection point and request format for this CVE is limited; treat any exploit descriptions outside the vendor advisory as unverified and validate them before use in testing or detection.

Because the outcome is remote code execution, a successful attack typically yields the privileges of the Nexus service account. From there an adversary may alter stored artifacts, steal credentials, move laterally, or establish persistence. No ransomware use is documented for this CVE in the supplied facts.

Am I affected? How to find it in your systems

Sonatype Nexus Repository is commonly deployed as an internal or DMZ-facing artifact manager for Maven, npm, Docker, and other package formats. It often runs as a standalone Java service or in containers on build networks, developer workstations, or shared infrastructure.

• Inventory hosts and containers for Nexus Repository installations (package names, service names, listening ports, and container images that reference Nexus).
• Record the installed version and edition from the application UI, administrative API, or filesystem metadata, then compare them to the fixed versions listed in the vendor advisory. Do not assume version ranges from third-party summaries.
• Note whether the instance is reachable from untrusted networks and which authentication and reverse-proxy controls sit in front of it.
• Review access and application logs for unusual requests to administrative or expression-evaluation endpoints, unexpected process spawns under the Nexus user, or outbound connections initiated by the Nexus process shortly after suspicious requests. Specific indicators of compromise are not provided in the facts; tune detections to your baseline and the vendor’s guidance.

How to remediate

Patch first. Apply the updates published by Sonatype for Nexus Repository exactly as described in the vendor advisory and in line with CISA’s required action to apply updates per vendor instructions. After upgrading, verify the running version and restart services as required so the fix is active.

• Restrict administrative and repository management interfaces to trusted networks and authenticated users only.
• Run the Nexus process with least privilege; avoid shared high-privilege service accounts.
• Keep the underlying OS, Java runtime, and reverse proxy patched and hardened.
• Enforce strong authentication, disable unused connectors or features, and monitor configuration drift so the repository cannot be silently re-exposed.

If you can't patch immediately

Until the vendor update is installed, reduce exposure with compensating controls:

• Segment the Nexus host so it is reachable only from build systems and administrators that require it; block direct internet access if not essential.
• Place a reverse proxy or WAF in front of the service and apply virtual-patching rules that reject anomalous payloads aimed at expression-language or administrative endpoints; tune and test rules to avoid breaking legitimate package traffic.
• Temporarily disable or tightly restrict any non-essential features or APIs that accept complex user input, if the vendor documentation allows it without breaking core repository functions.
• Increase monitoring: alert on new child processes of the Nexus service, unexpected outbound connections, changes to repository contents or user accounts, and authentication failures. Retain logs for forensic review.
• Ensure recent, tested backups of Nexus configuration and critical artifacts exist and are stored offline from the repository host.

If your data may have been exposed

Actively exploited remote-code-execution vulnerabilities are frequently used to establish footholds that lead to data theft or supply-chain compromise. If you have evidence of exploitation or cannot rule it out, treat the host and any credentials or artifacts it held as potentially compromised: rotate secrets, audit published packages for tampering, and follow your incident-response process. You can run a free exposure scan of your email addresses against known breach data to see whether associated accounts appear in public breach corpora while you complete containment and recovery.