CVE-2026-50771: Squirro Cognitive Search XSS Vulnerability

CVE-2026-50771 Overview

CVE-2026-50771 is a Cross-Site Scripting (XSS) vulnerability in Squirro Cognitive Search versions prior to 3.14.2. The flaw resides in the Email Notification, Create Evaluation Sets, and HTML Editor functions. A remote attacker can inject arbitrary script content that executes in the victim's browser session when the crafted content is rendered. Exploitation requires user interaction, and the scope is changed because injected script can affect resources beyond the vulnerable component. The vulnerability is tracked under CWE-79: Improper Neutralization of Input During Web Page Generation.

Critical Impact
Successful exploitation allows attackers to execute arbitrary JavaScript in a victim's browser, enabling session theft, credential harvesting, and unauthorized actions within Squirro Cognitive Search.

Affected Products

Squirro Cognitive Search versions prior to 3.14.2
Email Notification function
Create Evaluation Sets and HTML Editor functions

Discovery Timeline

2026-08-17 - CVE-2026-50771 published to NVD
2026-08-17 - Last updated in NVD database

Technical Details for CVE-2026-50771

Vulnerability Analysis

The vulnerability is a stored or reflected Cross-Site Scripting flaw located in three user-facing features of Squirro Cognitive Search. The Email Notification function, the Create Evaluation Sets function, and the HTML Editor function accept user-supplied input without sufficient output encoding. When the application later renders that input in a web context, the browser interprets attacker-controlled markup as executable script.

Because the CVSS vector indicates a scope change, the injected script can act on resources outside the vulnerable component's security boundary. This typically means the attacker can pivot from one application context into another authenticated user's session data.

The EPSS score is 0.184%, indicating a low probability of exploitation activity in the near term. No public proof-of-concept exploit or in-the-wild exploitation has been documented.

Root Cause

The root cause is improper neutralization of user input during web page generation ([CWE-79]). The three affected functions accept HTML or script content and reflect or store it without escaping characters such as <, >, ", and '. The HTML Editor function is particularly susceptible because it is designed to accept markup, requiring strict allowlisting and sanitization that the vulnerable versions do not enforce.

Attack Vector

A remote attacker crafts a malicious payload containing JavaScript and delivers it through one of the three affected functions. For the Email Notification and Create Evaluation Sets flows, the attacker either submits the payload directly if authenticated or lures an authenticated user into submitting it. When a victim views the resulting content in Squirro Cognitive Search, the browser executes the payload under the application's origin. Refer to the GitHub CVE-2026-50771 Repository for additional technical detail.

Detection Methods for CVE-2026-50771

Indicators of Compromise

Unexpected <script> tags, on* event handlers, or javascript: URIs stored in Email Notification templates, Evaluation Sets, or HTML Editor content.
Outbound HTTP requests from browsers of authenticated Squirro users to attacker-controlled domains shortly after loading application pages.
Session cookies or authentication tokens appearing in web server referer logs or in query strings to external endpoints.

Detection Strategies

Review application audit logs for user-submitted content in the affected functions containing HTML tags, event handlers, or encoded script fragments.
Inspect the browser Content Security Policy violation reports for blocked inline script executions originating from Squirro pages.
Query stored template and evaluation-set records for common XSS signatures such as onerror=, onload=, <svg, and <iframe.

Monitoring Recommendations

Enable and centrally collect Squirro application logs, then forward them to a SIEM for pattern-based alerting on XSS indicators.
Monitor for anomalous session activity such as concurrent logins from disparate geolocations following template edits.
Track outbound web traffic from user workstations to newly registered or uncategorized domains after Squirro usage.

How to Mitigate CVE-2026-50771

Immediate Actions Required

Upgrade Squirro Cognitive Search to version 3.14.2 or later on all production and non-production instances.
Audit existing Email Notification templates, Evaluation Sets, and HTML Editor content for previously injected scripts and remove them.
Rotate session tokens and require re-authentication for all users following the upgrade.

Patch Information

Squirro addressed the issue in Squirro Cognitive Search version 3.14.2. Consult the Squirro Cognitive Search Documentation for release notes and upgrade instructions.

Workarounds

Restrict access to the Email Notification, Create Evaluation Sets, and HTML Editor functions to trusted administrative users until the patch is applied.
Deploy a Web Application Firewall rule to inspect and block requests containing script tags or event-handler attributes bound for the affected endpoints.
Enforce a strict Content Security Policy that disallows inline scripts and untrusted script sources for the Squirro application origin.

bash

# Example CSP header to reduce XSS impact until patching completes
Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'self'