CVE-2025-20373 identifies a vulnerability in the Splunk Add-on for Palo Alto Networks prior to version 2.0.2, where sensitive client secrets are written in plaintext to the _internal index logs during the configuration of new Data Security Accounts. The _internal index is a special Splunk index used for internal logging and diagnostic data, which by default is accessible only to users with administrative privileges. This vulnerability arises because the add-on fails to mask or encrypt these secrets before logging, thereby exposing them to anyone with access to these internal logs. Exploiting this vulnerability requires either local file system access to the Splunk server logs or administrative access to the internal indexes, which is typically limited to Splunk administrators. The CVSS 3.1 base score is 2.7, reflecting low severity due to the requirement for high privileges (PR:H), no user interaction (UI:N), network attack vector (AV:N), and limited impact confined to confidentiality (C:L) without affecting integrity or availability. While the vulnerability does not allow remote exploitation without elevated privileges, it poses a risk of credential leakage within trusted environments, potentially facilitating lateral movement or privilege escalation if attackers gain admin-level access. The recommended mitigation includes reviewing and strictly limiting roles and capabilities related to internal index access, ensuring only trusted administrators have such permissions, and upgrading the add-on to version 2.0.2 or later once available. Organizations should also audit logs for any unauthorized access and consider encrypting sensitive configuration data where possible.

For European organizations, the primary impact of this vulnerability is the potential exposure of sensitive client secrets used by the Splunk Add-on for Palo Alto Networks. Although exploitation requires administrative privileges or local access, if an attacker gains such access, they could retrieve these secrets from logs, aiding further compromise of network security monitoring or Palo Alto Networks integrations. This could lead to unauthorized data access or manipulation within security monitoring environments, undermining trust in security operations. The vulnerability does not directly affect system availability or integrity, but the confidentiality breach could facilitate more severe attacks if combined with other vulnerabilities or insider threats. Organizations in sectors with stringent data protection regulations, such as finance, healthcare, and critical infrastructure, could face compliance risks if sensitive information is leaked. Additionally, the exposure of credentials could weaken the security posture of incident response and threat detection capabilities, potentially delaying detection of malicious activities. The limited exploitability reduces the immediate risk, but the presence of plaintext secrets in logs is a poor security practice that should be remediated promptly to maintain defense-in-depth.

1. Immediately review and audit Splunk roles and capabilities, ensuring that access to the _internal index is strictly limited to trusted administrator-level roles only. 2. Implement role-based access controls (RBAC) with the principle of least privilege, removing unnecessary admin privileges from users who do not require them. 3. Upgrade the Splunk Add-on for Palo Alto Networks to version 2.0.2 or later as soon as the patch is available to eliminate the vulnerability. 4. Monitor and audit internal logs for any unauthorized access or suspicious activity related to the _internal index. 5. Consider encrypting sensitive configuration data and secrets outside of logging mechanisms to prevent plaintext exposure. 6. Employ network segmentation and host-based protections to limit local access to Splunk servers and their log files. 7. Educate administrators on secure handling of credentials and the risks of logging sensitive information. 8. Regularly review Splunk documentation and security advisories to stay informed about best practices and updates related to role definitions and data security.