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MaxkbApplication

CVE-2026-39425

MEDIUM · 5.4 CVSS v3.1 Published 2026-04-14
Fix available
A fix is available. Upgrade to 2.8.0 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a Stored Cross-Site Scripting (XSS) vulnerability that allows authenticated users to inject arbitrary HTML and JavaScript into the Application prologue (Opening Remarks) field by wrapping malicious payloads in <html_rander> tags. The backend fails to sanitize or encode HTML entities in the prologue field when applications are created or updated via the /admin/api/workspace/{workspace_id}/application endpoint, storing the raw payload directly in the database. The frontend then renders this content using an innerHTML-equivalent mechanism, trusting <html_rander>-wrapped content to be safe, which enables persistent DOM-based Stored XSS execution against any visitor who opens the affected chatbot interface. Exploitation can lead to session hijacking, unauthorized actions performed on behalf of victims (such as deleting workspaces or applications), and sensitive data exposure. This issue has been fixed in version 2.8.0.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

MaxKB versions 2.7.1 and below have a Stored XSS vulnerability in the Application prologue field. Authenticated users can inject malicious HTML/JavaScript payloads wrapped in <html_rander> tags via the /admin/api/workspace/{workspace_id}/application endpoint. The backend stores unsanitized input directly, and the frontend renders it via innerHTML, treating <html_rander>-wrapped content as safe, enabling persistent XSS against anyone viewing the affected chatbot.

MitigationUpgrade to MaxKB version 2.8.0 or later, which contains the fix for proper sanitization and encoding of the prologue field content.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
MaxkbApplication
Affected:< 2.8.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check MaxKB version
    Locate the installed MaxKB version by querying the application's version endpoint, checking the Docker image tag, or reviewing the installation manifest. Compare the version number to the affected range (anything below 2.8.0).
    Affected if The installed version is 2.7.1 or below, or any version less than 2.8.0.
  2. Identify applications with prologue fields
    Query the application configuration via the /admin/api/workspace/{workspace_id}/application endpoint or review the database table storing application settings. Look for any applications that have a prologue field defined.
    Affected if There exist applications with a non-empty prologue field configuration.
  3. Inspect prologue field content for malicious tags
    Examine the stored prologue field values in the application database or via API response. Search specifically for the presence of <html_rander> tags or any raw HTML/JavaScript content that appears unsanitized.
    Affected if The prologue field contains <html_rander> tags wrapping content, or raw HTML/script tags that were not properly encoded.
  4. Verify frontend rendering method
    Inspect the frontend code that renders the application prologue. Look for uses of innerHTML, v-html, or similar methods that render unescaped HTML content.
    Affected if The prologue is rendered using innerHTML or equivalent unescaped HTML rendering without sanitization.

A user is affected if they are running MaxKB version below 2.8.0 AND have applications with prologue fields that contain <html_rander> tags or unsanitized HTML content rendered via innerHTML.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.8.0 or later
Fixed in 2.8.0
Interim mitigation

Upgrade to MaxKB version 2.8.0 or later, which contains the fix for proper sanitization and encoding of the prologue field content.

Recommended fix High confidence

MaxKB version 2.8.0

  1. Upgrade MaxKB to version 2.8.0 or later to remediate the Stored XSS vulnerability in the Application prologue field.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Maxkb Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-39425 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data