CVE-2026-20142 is a vulnerability affecting multiple versions of Splunk Enterprise (below 10.2.0, 10.0.2, 9.4.7, 9.3.9, and 9.2.11) where sensitive information is improperly logged in plaintext within the _internal index of a Splunk Search Head Cluster (SHC) deployment. Specifically, the RSA accessKey value from the authentication.conf configuration file is exposed. This key is critical for authentication processes and its exposure can provide attackers with valuable information to compromise the system further. The vulnerability arises due to insufficient protection of sensitive data in log files, categorized under CWE-532 (Information Exposure Through Log Files). Exploitation requires a user to have a role with access to the _internal index, which typically implies some level of privileged access, but no user interaction is needed. The CVSS 3.1 score of 6.8 reflects a medium severity with high confidentiality, integrity, and availability impacts, but limited attack vector scope (adjacent network) and requiring privileges. No public exploits are known at this time, but the exposure of cryptographic keys in logs is a significant risk that could facilitate lateral movement or privilege escalation within affected environments.

The exposure of the RSA accessKey in plaintext within logs can lead to serious security consequences for organizations using affected Splunk Enterprise versions. An attacker with access to the _internal index could retrieve this key and potentially impersonate legitimate authentication processes, leading to unauthorized access, data breaches, or manipulation of log data and system configurations. This compromises confidentiality, integrity, and availability of the Splunk environment and potentially connected systems. Given Splunk's widespread use in security monitoring and operational intelligence, exploitation could undermine trust in security monitoring, delay incident response, and enable attackers to hide their activities. Organizations relying on Splunk for critical security functions may face increased risk of data exfiltration, insider threats, and compliance violations if this vulnerability is exploited.

To mitigate CVE-2026-20142, organizations should upgrade Splunk Enterprise to versions 10.2.0, 10.0.2, 9.4.7, 9.3.9, or 9.2.11 or later, where this issue is resolved. Until upgrades can be applied, restrict access to the _internal index to only the minimum necessary roles, ensuring that only trusted administrators have access. Review and audit roles with _internal index permissions to detect any unnecessary privileges. Implement strict monitoring and alerting on access to sensitive logs and configuration files. Consider encrypting sensitive configuration files and keys where possible, and avoid logging sensitive authentication keys in plaintext. Regularly review Splunk logs for signs of unauthorized access or suspicious activity. Additionally, enforce network segmentation and strong authentication controls to limit the attack surface. Finally, educate administrators about the risks of exposing sensitive keys in logs and the importance of applying security patches promptly.