Unauthorized Access via API Key in Sonatype Nexus Repository

Executive Summary

CVE-2026-11403 is a vulnerability in Sonatype Nexus Repository Manager 3.x versions prior to 3.93.0. It involves insufficient entropy in the generation of API keys for format-specific realms, such as NuGet API Key, Docker Bearer Token, npm Bearer Token, or Conan.

This weakness allows a remote attacker to recover a valid user's API key by exploiting the predictable nature of the key generation process. If successful, the attacker could gain unauthorized access to repository operations, including read or write permissions, depending on the targeted user's access level.

• The vulnerability requires three conditions to be exploitable: the format-specific API key realm must be enabled, the targeted user must have an active API key, and the attacker must identify or guess a valid username.

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Detection Guidance

Detecting this vulnerability involves checking if your Sonatype Nexus Repository Manager instance meets the conditions for exploitation. Specifically, you need to verify if a format-specific API key realm (NuGet API Key, Docker Bearer Token, or npm Bearer Token) is enabled and if users have active API keys.

• Check if the vulnerable realms are enabled: Log in to the Nexus Repository Manager admin interface, navigate to 'Security' > 'Realms', and look for 'NuGet API Key Realm', 'Docker Bearer Token Realm', or 'npm Bearer Token Realm' in the active realms list.
• Verify if users have active API keys: In the admin interface, go to 'Security' > 'Users', select a user, and check if they have an API key listed under their profile. This applies to users who might be targeted by an attacker.
• Check the Nexus Repository Manager version: Ensure your instance is not running a version prior to 3.93.0. You can find the version in the admin interface under 'System' > 'Information' or by checking the footer of the web interface.

There are no specific commands to detect this vulnerability directly on the network, as it is related to the configuration and API key generation within the Nexus Repository Manager itself. Detection relies on manual verification of the conditions mentioned above.

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Impact Analysis

If you are using an affected version of Sonatype Nexus Repository Manager (prior to 3.93.0) with format-specific API key realms enabled, this vulnerability could impact you in the following ways:

• Unauthorized access to your repository operations: An attacker could gain access to your repository with the same permissions as the targeted user, potentially allowing them to read, modify, or delete sensitive data.
• Data breaches: If the compromised user has elevated privileges, the attacker could exfiltrate sensitive information stored in the repository, such as proprietary code, credentials, or other confidential data.
• Repository integrity risks: The attacker could introduce malicious code or artifacts into the repository, which could then be distributed to downstream users or systems.
• Operational disruption: Unauthorized modifications or deletions could disrupt your development or deployment pipelines, leading to downtime or operational inefficiencies.

Even after upgrading to version 3.93.0 or later, existing API keys remain valid but should be regenerated to mitigate the risk.

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Compliance Impact

This vulnerability could have significant implications for compliance with various standards and regulations, depending on the nature of the data stored or managed in the affected repository:

• GDPR (General Data Protection Regulation): If the repository contains personal data of EU citizens, unauthorized access could lead to a data breach. GDPR requires organizations to implement appropriate security measures to protect personal data. A breach could result in fines of up to 4% of global annual revenue or €20 million, whichever is higher, as well as reputational damage.
• HIPAA (Health Insurance Portability and Accountability Act): If the repository stores or processes protected health information (PHI), unauthorized access could constitute a breach under HIPAA. Organizations could face penalties ranging from $100 to $50,000 per violation, with a maximum of $1.5 million per year for each violation category.
• PCI DSS (Payment Card Industry Data Security Standard): If the repository handles payment card data, a breach could violate PCI DSS requirements, leading to fines, increased transaction fees, or even the loss of the ability to process credit card payments.
• SOC 2: For organizations undergoing SOC 2 audits, this vulnerability could indicate a failure to meet the security and confidentiality trust services criteria, potentially resulting in a qualified or adverse audit opinion.
• ISO 27001: This standard requires organizations to implement risk management processes and controls to protect information assets. A vulnerability like this could indicate a failure to adequately assess and mitigate risks, potentially leading to non-conformities during an audit.

To maintain compliance, organizations should promptly upgrade to the patched version (3.93.0 or later) and regenerate all existing API keys. Additionally, they should review access logs for signs of unauthorized activity and report any breaches to the relevant authorities as required by applicable regulations.

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Mitigation Strategies

To mitigate this vulnerability, follow these immediate steps:

• Upgrade to Sonatype Nexus Repository Manager version 3.93.0 or later. This version includes fixes for the insufficient entropy issue in API key generation.
• Regenerate all existing API keys for users, even after upgrading. The improved algorithm in version 3.93.0 does not automatically invalidate existing keys, so manual regeneration is necessary to ensure security.
• Disable format-specific API key realms if they are not required. Navigate to 'Security' > 'Realms' in the admin interface and remove 'NuGet API Key Realm', 'Docker Bearer Token Realm', or 'npm Bearer Token Realm' from the active realms list.
• Monitor user accounts and repository operations for any suspicious activity, such as unauthorized access attempts or unusual repository operations.
• Educate users about the importance of API key security and encourage them to follow best practices, such as not sharing keys and regenerating them periodically.

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