CVE-2026-76351 in Splunk
Summary
by MITRE • 08/20/2026
In Splunk Enterprise versions below 10.4.2, 10.2.6, 10.0.9, and 9.4.14, and Splunk Secure Gateway versions below 3.10.9, 3.9.23, and 3.8.70, a user who does not hold the "admin" or "power" Splunk roles could use crafted report notification data to cause Splunk Secure Gateway to send a request to the Splunk Enterprise Representational State Transfer (REST) API using a system-level session token and modify the Splunk platform configuration. The user could then obtain a session token without a password and use it to access all relevant data and affect system integrity. The vulnerability is possible because Splunk Secure Gateway does not validate decoded report notification identifiers before using them to construct requests to the Splunk Enterprise REST API.
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Analysis
by VulDB Data Team • 08/20/2026
The identified vulnerability represents a critical authentication bypass and privilege escalation flaw within the Splunk ecosystem, specifically affecting interactions between Splunk Secure Gateway and Splunk Enterprise instances running versions prior to 10.4.2, 10.2.6, 10.0.9, and 9.4.14, as well as Splunk Secure Gateway versions below 3.10.9, 3.9.23, and 3.8.70. This security issue stems from a fundamental failure in input validation within the Splunk Secure Gateway component when processing report notification data. The architecture relies on Splunk Secure Gateway to act as an intermediary that forwards certain requests to the core Splunk Enterprise REST API using elevated system-level session tokens. However, the gateway fails to adequately validate decoded identifiers associated with these notifications before constructing and executing subsequent API calls. This lack of rigorous validation allows a malicious actor who possesses only low-privileged roles, such as those lacking admin or power permissions, to manipulate the notification payload in ways that exploit this trust boundary.
From a technical perspective, the core flaw is classified under CWE-20 Improper Input Validation and CWE-798 Use of Hard-coded Credentials if system tokens are considered static secrets within the gateway configuration context. The attacker crafts specific report notification data containing malicious identifiers or parameters designed to trick the Splunk Secure Gateway into interpreting them as legitimate administrative commands. When the gateway processes this crafted input, it utilizes its own high-privilege session token to send a request to the Splunk Enterprise REST API. Because the validation logic is bypassed, the enterprise instance accepts these requests as if they originated from an authorized administrator. This mechanism effectively allows the low-privileged user to execute administrative functions remotely without possessing the necessary credentials or role assignments within the Splunk platform itself.
The operational impact of this vulnerability is severe, leading directly to a complete compromise of system integrity and data confidentiality. By exploiting this flaw, an attacker can modify critical Splunk platform configurations, potentially disabling security controls, altering logging mechanisms, or changing user permissions. More critically, the exploitation chain enables the acquisition of valid session tokens without requiring a password. Once such a token is obtained through this indirect method, it grants unrestricted access to all relevant data stored within the Splunk environment. This includes sensitive logs, search results, and potentially proprietary business intelligence data. The ability to affect system integrity means that an attacker could also establish persistence mechanisms or create backdoors for future unauthorized access, turning a low-privilege account into a full administrative foothold on the infrastructure.
In terms of threat modeling, this vulnerability aligns with MITRE ATT&CK techniques related to Privilege Escalation and Defense Evasion. Specifically, it reflects patterns associated with exploiting trust relationships between services (T1648) and leveraging existing system resources for unauthorized access. The attack vector is remote if the Splunk Secure Gateway is exposed to untrusted networks, making it a high-risk issue in distributed deployments where secure gateways are used to manage traffic across network boundaries. Attackers can leverage this flaw during the initial compromise phase or as part of lateral movement strategies within an environment that has already been partially infiltrated by lower-privileged accounts.
Mitigation requires immediate action from system administrators and security operations teams. The primary remediation step is to upgrade Splunk Enterprise, Splunk Secure Gateway, and any related components to their respective patched versions: 10.4.2 or later for the main enterprise platform, and 3.10.9, 3.9.23, or 3.8.70 or later for the secure gateway component. Until patches are applied, organizations should implement strict network segmentation to ensure that Splunk Secure Gateway instances are not accessible from untrusted networks. Additionally, reviewing access control lists and ensuring that report notification features are restricted to only those users who absolutely require them can reduce the attack surface. Monitoring logs for unusual REST API calls originating from gateway IPs or involving unexpected parameter structures may also help in detecting active exploitation attempts of this vulnerability.