CVE-2026-76311 Overview
CVE-2026-76311 is a broken access control vulnerability in Splunk Enterprise that allows unauthenticated attackers holding an embedded report token to download dispatch archives for embedded report search jobs. The archive contains exposed session material that attackers can use to access relevant data and affect system integrity on the Splunk platform instance. The flaw exists because the embedded report authorization flow does not block dispatch archive download requests before Splunk begins streaming the archive. The vulnerability is classified under [CWE-284] Improper Access Control and affects multiple supported release branches.
Critical Impact
An unauthenticated user with an embedded report token can retrieve session material from dispatch archives, gaining access to Splunk data and compromising instance integrity.
Affected Products
- Splunk Enterprise versions below 10.4.2
- Splunk Enterprise versions below 10.2.6 and 10.0.9
- Splunk Enterprise versions below 9.4.14
Discovery Timeline
- 2026-08-19 - CVE-2026-76311 published to NVD
- 2026-08-20 - Last updated in NVD database
Technical Details for CVE-2026-76311
Vulnerability Analysis
Splunk Enterprise supports embedded reports that let external consumers render report output through a token-based authorization flow. Each scheduled report execution creates a dispatch directory containing intermediate search artifacts, results, and session material used by the executing user context. Embedded report tokens are intended to grant narrow, read-only access to the rendered report output only.
The authorization flow evaluates the token but does not gate requests for the dispatch archive endpoint before Splunk begins transmitting the archive to the requester. An unauthenticated caller with a valid embedded report token can therefore request the dispatch archive and receive it, along with the session material embedded in the archive contents. Because the archive contains reusable session data, an attacker can pivot to broader read access and perform actions that affect system integrity on the instance.
Root Cause
The root cause is missing authorization enforcement on the dispatch archive download path when the request originates from the embedded report flow. Splunk starts sending archive data to the requester before verifying that the token holder is authorized to receive dispatch-level artifacts. The token scope for embedded reports is not correctly propagated to the archive endpoint's access checks.
Attack Vector
Exploitation requires network access to the Splunk Enterprise instance and possession of an embedded report token. Tokens can be obtained through exposed embed URLs, cached links, log leakage, or interception. Once the attacker holds a token, they issue a crafted request to the dispatch archive endpoint associated with the embedded report search job. Splunk returns the archive, and the attacker extracts session material to escalate access. No user interaction and no prior authenticated Splunk account are required.
Detection Methods for CVE-2026-76311
Indicators of Compromise
- Unexpected HTTP GET requests to dispatch archive URLs (paths containing /services/search/jobs/<sid>/results or dispatch directory download endpoints) originating from clients presenting embedded report tokens.
- Repeated archive downloads for the same search ID from multiple source IP addresses within a short time window.
- Anomalous access to the $SPLUNK_HOME/var/run/splunk/dispatch/ directory or its archived exports outside of scheduled report execution windows.
Detection Strategies
- Review Splunk _internal and _audit indexes for action=search, info=granted, and dispatch archive access events tied to embedded report tokens rather than authenticated users.
- Correlate embedded report token issuance with subsequent archive download endpoint hits and alert when a single token is used to fetch dispatch content.
- Baseline normal embedded report traffic per report ID and flag deviations in request volume, source geography, or user agent.
Monitoring Recommendations
- Enable and forward Splunk web access logs to a central data lake for retention and correlation across the audit trail.
- Instrument reverse proxies fronting Splunkweb to log full request paths and token identifiers for embedded report requests.
- Track outbound archive response sizes from Splunk to identify large dispatch archive transfers that fall outside expected report rendering patterns.
How to Mitigate CVE-2026-76311
Immediate Actions Required
- Upgrade Splunk Enterprise to 10.4.2, 10.2.6, 10.0.9, 9.4.14, or later on the corresponding release branch.
- Rotate or revoke all outstanding embedded report tokens issued before the upgrade to invalidate any material that may already have been exposed.
- Audit web access logs for prior dispatch archive downloads that used embedded report tokens and treat any confirmed downloads as a data exposure event.
Patch Information
Splunk released fixed versions in the 10.4.2, 10.2.6, 10.0.9, and 9.4.14 release trains. Refer to the Splunk Security Advisory SVD-2026-0801 for full patch details and upgrade guidance.
Workarounds
- Disable embedded reports on the instance until the patch is applied. See Additional configuration for embedded reports in the Splunk documentation.
- Restrict network access to Splunkweb through firewall rules or reverse proxy allow-lists to limit exposure of the dispatch archive endpoint.
- Terminate scheduled embedded report jobs that hold active dispatch directories and clear the dispatch cache to purge any archives that could be retrieved with existing tokens.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
