CVE-2026-76349: Splunk Enterprise Auth Bypass Vulnerability

CVE-2026-76349 Overview

CVE-2026-76349 is a Search Processing Language (SPL) injection vulnerability in Splunk Enterprise. The flaw allows an unauthenticated attacker to trick an authenticated user into executing arbitrary SPL commands through a crafted Splunk Web link. Splunk Web substitutes form token values passed through the URL into SPL searches without neutralizing them, enabling command injection under the authenticated user's permissions. The vulnerability is classified under [CWE-943] (Improper Neutralization of Special Elements in Data Query Logic).

Critical Impact
An attacker who successfully phishes an authenticated user can execute SPL commands with that user's privileges, potentially accessing all data the victim can query.

Affected Products

Splunk Enterprise versions below 10.2.6
Splunk Enterprise versions below 10.0.9
Splunk Enterprise versions below 9.4.14

Discovery Timeline

2026-08-19 - CVE-2026-76349 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-76349

Vulnerability Analysis

The vulnerability resides in Splunk Web's handling of form token values supplied through URL parameters. Splunk Web substitutes these token values directly into SPL searches without applying neutralization or escaping. An attacker can craft a URL that embeds malicious SPL syntax within token parameters. When an authenticated user opens the link, Splunk Web resolves the tokens into the target search, and the injected SPL executes under the victim's permissions.

The attack requires user interaction, and the attacker must successfully phish the target into clicking the crafted link. The unauthenticated attacker cannot exploit the vulnerability at will without victim participation. Splunk Enterprise 10.4 and above are not affected by this issue.

Root Cause

The root cause is improper neutralization of URL-supplied form token values before they are inserted into SPL query context. Splunk Web treats URL-provided token values as trusted input and interpolates them directly into search strings. This behavior violates the principle of separating data from query logic, allowing SPL syntax supplied by an attacker to be parsed as executable search commands rather than literal string data.

Attack Vector

The attack proceeds in three stages. First, the attacker crafts a Splunk Web URL that includes form token parameters loaded with malicious SPL fragments. Second, the attacker delivers the URL to an authenticated Splunk user through phishing, chat, email, or another social channel. Third, when the victim clicks the link within an active Splunk Web session, Splunk substitutes the token values into a dashboard or search context and runs the resulting SPL under the victim's identity. Refer to the Splunk Security Advisory SVD-2026-0801 for additional technical detail.

Detection Methods for CVE-2026-76349

Indicators of Compromise

Splunk Web access logs containing unusual URL parameters with SPL keywords such as search, |, eval, or outputlookup embedded in token values.
Audit log entries showing SPL searches executed by users that do not match their normal dashboard or search patterns.
HTTP referrer headers pointing to external domains for requests that invoke internal Splunk dashboards.

Detection Strategies

Review the _audit index for search activity correlated with inbound clicks on Splunk Web URLs containing suspicious token parameters.
Alert on SPL commands executed through dashboard token substitution that reference sensitive indexes outside the user's typical scope.
Correlate email or web proxy logs with Splunk Web sessions to identify phishing lures that direct users to crafted Splunk URLs.

Monitoring Recommendations

Enable verbose access logging on Splunk Web and forward logs to a centralized analytics platform for anomaly detection.
Baseline each user's typical SPL command patterns and alert when deviations occur following external link clicks.
Monitor for outbound data staging commands such as outputcsv, outputlookup, or sendemail triggered from dashboard contexts.

How to Mitigate CVE-2026-76349

Immediate Actions Required

Upgrade Splunk Enterprise to version 10.2.6, 10.0.9, 9.4.14, or 10.4 and above.
Notify users of active phishing risk and instruct them to avoid clicking Splunk Web links from untrusted sources.
Review recent Splunk Web access logs for suspicious URL patterns targeting form tokens.

Patch Information

Splunk has released fixed versions addressing this vulnerability. Upgrade Splunk Enterprise to 10.2.6, 10.0.9, 9.4.14, or any release in the 10.4 branch or later. See the Splunk Security Advisory SVD-2026-0801 for full remediation guidance.

Workarounds

Restrict Splunk Web access to trusted networks using firewall or reverse proxy rules until patches are applied.
Enforce strict Content Security Policy and referrer checks at the reverse proxy layer to reduce phishing effectiveness.
Educate users to authenticate to Splunk Web in isolated browser sessions and to inspect URLs before opening dashboard links.

bash

# Verify installed Splunk Enterprise version
$SPLUNK_HOME/bin/splunk version

# Example upgrade command (Linux tar install)
tar xvzf splunk-10.2.6-linux-x86_64.tgz -C /opt
$SPLUNK_HOME/bin/splunk restart