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Cross-Site-Scripting (XSS) represents a widespread web application vulnerability where malicious scripts are injected into trusted websites, subsequently executing inside a victim’s browser context. In the context of the Indico event management system, the vulnerability specifically targets the minute editor conflict resolution user interface. When multiple authorized contributors concurrently edit identical event minutes, the application renders collision data to help resolve differences. If an attacker with permission to author content injects maliciously crafted script tags or event handlers into the minute text, the conflict resolution screen fails to properly sanitize or neutralize this input before rendering. When another user views this conflict UI, the unescaped payload executes directly within their authenticated session, potentially enabling session hijacking, data exfiltration, or unauthorized interface manipulation within the application origin.
DailyCVE Form:
Platform: Indico
Version: < 3.3.13
Vulnerability : XSS
Severity: Medium
date: 2026-08-25
Prediction: 2026-08-25
What Undercode Say
The vulnerability stems from improper neutralization of user-supplied input rendered dynamically inside conflict resolution alerts or merge text views. Specifically, the application templates display raw strings from concurrent edits without applying strict context-aware HTML escaping, enabling arbitrary script execution via crafted input payloads.
Clone the target indico repository for inspection git clone https://github.com/indico/indico.git cd indico Checkout version prior to patch git checkout v3.3.12 Search for minute editor conflict handling templates git grep -n "minutes" indico/modules/
Conceptual vulnerable rendering context in Python/Jinja template handling
from markupsafe import Markup
def render_conflict_notice(user_input_text):
Vulnerable implementation lacking proper escaping filter
return Markup(f"
<div class='conflict'>Conflict content: {user_input_text}</div>
")
Exploit: (Educational Purposes!)
An attacker can exploit this flaw by leveraging legitimate access to input malicious payloads into event minutes, triggering a race condition or concurrent edit state.
Malicious payload injected into event minutes to trigger XSS upon conflict resolution view <img src=x onerror=alert(document.cookie)>
1. Authenticate to the Indico platform with low-privileged speaker or editor permissions.
2. Open an event minute document and submit conflicting edits simultaneously with another user.
3. Inject the payload string into the content block to force conflict UI generation.
4. Wait for a targeted administrator or user to access the conflict resolution page where the payload executes.
Protection: from this CVE
To protect your Indico deployment against this cross-site scripting vector, you should immediately update the software package to version 3.3.13 or later. Additionally, enable Content Security Policy mitigations in your configuration file by setting `CSP_ENABLED = True` inside indico.conf, which serves as a robust defense-in-depth mechanism against arbitrary script injection regardless of application-level bugs.
Impact
Successful exploitation of this vulnerability permits an attacker to execute arbitrary JavaScript code within the browser of any user reviewing conflicting event minutes. This can lead to the theft of sensitive session cookies, unauthorized interaction with the application interface on behalf of the victim, or disclosure of internal platform metadata accessible to the authenticated viewer.
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Sources:
Reported By: github.com
Extra Source Hub:
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