CVE-2026-76279 in Splunk
Summary
by MITRE • 10/07/2026
In Splunk Enterprise versions below 10.4.3, 10.2.7, 10.0.10, and 9.4.15, a user that holds a role with the run_collect capability could use the collect Search Processing Language (SPL) command to write events to internal indexes outside the index access configured for the role. The vulnerability is possible because Splunk Enterprise does not normalize whitespace in an index name before applying configured index-access restrictions for the role. For more information see collect (https://help.splunk.com/en/splunk-enterprise/search/spl-search-reference/10.4/search-commands/collect), Define roles on the Splunk platform with capabilities (https://help.splunk.com/en/splunk-enterprise/administer/manage-users-and-security/10.4/manage-splunk-platform-users-and-roles/define-roles-on-the-splunk-platform-with-capabilities), and How indexing works (https://help.splunk.com/en/splunk-enterprise/administer/manage-indexers-and-indexer-clusters/10.4/indexing-overview/how-indexing-works) in the Splunk documentation.
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Analysis
by VulDB Data Team • 10/07/2026
A critical access control vulnerability exists within Splunk Enterprise versions prior to 10.4.3, 10.2.7, 10.0.10, and 9.4.15, allowing users with specific permissions to bypass intended data isolation boundaries. The flaw resides in the implementation of index access restrictions for user roles, specifically concerning how input parameters are processed before security checks are applied. When a user possesses the run_collect capability, they can execute the collect Search Processing Language command, which is designed to write search results into specified indexes. However, due to insufficient normalization of whitespace characters within the target index name parameter, the system fails to correctly match the requested destination against the role's authorized index list. This discrepancy enables an attacker or malicious insider to direct sensitive data into internal indexes that are strictly prohibited for their assigned role level, effectively circumventing administrative access controls and potentially exposing confidential information stored in those restricted locations.
The technical root cause of this vulnerability is a lack of input sanitization regarding whitespace handling during the validation phase of index name resolution. In secure software design, string inputs used to identify resources such as database tables or file paths must be normalized to ensure consistent matching against access control lists. Splunk Enterprise failed to strip or standardize leading and trailing spaces, or potentially internal spacing variations, in the index identifier provided by the user. Consequently, a role restricted from accessing an index named "internal_audit" might still successfully write events to it if the request specifies " internal_audit " with surrounding whitespace. This logic error exploits the gap between human-readable input formatting and machine-level string comparison operations used for permission verification. The vulnerability aligns closely with CWE-284, which describes Improper Access Control, as well as CWE-798, involving the use of hardcoded or weak credentials in this context of privilege escalation through configuration bypass.
The operational impact of this flaw is significant from a data governance and compliance perspective. By writing events to unauthorized internal indexes, an attacker can exfiltrate high-value telemetry data that was intended for restricted administrative analysis only. This breach undermines the principle of least privilege, allowing lower-privileged users to access or manipulate data reserved for security administrators or auditors. In regulated environments such as those adhering to PCI DSS or HIPAA standards, this capability could lead to non-compliance due to unauthorized disclosure of protected health information or cardholder data. Furthermore, if the internal indexes contain logs related to system integrity or authentication events, an attacker might alter these records to cover their tracks, thereby compromising audit trails and hindering forensic investigations. The ability to write to arbitrary indexes also poses a risk of index corruption or resource exhaustion if large volumes of maliciously crafted data are injected into critical storage locations not designed for such ingestion patterns.
To mitigate this vulnerability, organizations must immediately upgrade Splunk Enterprise to version 10.4.3, 10.2.7, 10.0.10, or 9.4.15, where the input normalization logic has been corrected to strictly enforce index access policies regardless of whitespace variations in user input. Until patching is complete, administrators should review and restrict roles that possess the run_collect capability, ensuring that only trusted users with a demonstrated need for this function are granted it. Additionally, implementing strict monitoring on write operations to internal indexes can help detect anomalous activity indicative of exploitation attempts. Security teams should also audit existing role configurations to ensure that index access lists are as restrictive as possible, minimizing the blast radius in case of future privilege escalation vulnerabilities. Regular reviews of Splunk documentation regarding secure configuration practices and adherence to industry standards like MITRE ATT&CK technique T1078 for valid credentials abuse can further harden the environment against such logical flaws.