CVE-2026-39426: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in 1Panel-dev MaxKB
MaxKB versions 2. 7. 1 and below have a stored Cross-Site Scripting (XSS) vulnerability in the frontend components that handle custom <iframe_render> tags. Unsanitized HTML content is rendered in an iframe with a sandbox attribute that still allows script execution and same-origin access, enabling injected scripts to escape the iframe and execute in the parent window. This vulnerability can lead to session hijacking, unauthorized actions, and exposure of sensitive data. The issue is fixed in version 2. 8. 0.
AI Analysis
Technical Summary
CVE-2026-39426 is a stored XSS vulnerability in MaxKB (versions ≤ 2.7.1) where the MdRenderer.vue component parses custom <iframe_render> tags from LLM responses or application configurations without proper sanitization. The unsanitized HTML is passed to IframeRender.vue, which renders it inside an iframe using the srcdoc attribute with sandbox="allow-scripts allow-same-origin". This sandbox configuration permits scripts to run and maintain same-origin privileges, allowing malicious scripts to escape the iframe context and execute JavaScript in the parent window via window.parent. Since the vulnerable Prologue content is rendered for any user accessing the chat interface, this results in a high-impact stored XSS vulnerability. The vulnerability has been addressed in MaxKB version 2.8.0.
Potential Impact
Exploitation of this vulnerability allows attackers to execute arbitrary JavaScript in the context of the parent window for any user visiting the affected chat interface. This can lead to session hijacking, unauthorized actions on behalf of the user, and exposure of sensitive information. The CVSS 4.0 base score is 5.1 (medium severity), reflecting network attack vector, low complexity, and partial impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Upgrade MaxKB to version 2.8.0 or later, where this stored XSS vulnerability has been fixed. Since the vendor advisory confirms the fix in 2.8.0, applying this official update is the recommended remediation. No additional mitigations are specified or required beyond upgrading.
CVE-2026-39426: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in 1Panel-dev MaxKB
Description
MaxKB versions 2. 7. 1 and below have a stored Cross-Site Scripting (XSS) vulnerability in the frontend components that handle custom <iframe_render> tags. Unsanitized HTML content is rendered in an iframe with a sandbox attribute that still allows script execution and same-origin access, enabling injected scripts to escape the iframe and execute in the parent window. This vulnerability can lead to session hijacking, unauthorized actions, and exposure of sensitive data. The issue is fixed in version 2. 8. 0.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-39426 is a stored XSS vulnerability in MaxKB (versions ≤ 2.7.1) where the MdRenderer.vue component parses custom <iframe_render> tags from LLM responses or application configurations without proper sanitization. The unsanitized HTML is passed to IframeRender.vue, which renders it inside an iframe using the srcdoc attribute with sandbox="allow-scripts allow-same-origin". This sandbox configuration permits scripts to run and maintain same-origin privileges, allowing malicious scripts to escape the iframe context and execute JavaScript in the parent window via window.parent. Since the vulnerable Prologue content is rendered for any user accessing the chat interface, this results in a high-impact stored XSS vulnerability. The vulnerability has been addressed in MaxKB version 2.8.0.
Potential Impact
Exploitation of this vulnerability allows attackers to execute arbitrary JavaScript in the context of the parent window for any user visiting the affected chat interface. This can lead to session hijacking, unauthorized actions on behalf of the user, and exposure of sensitive information. The CVSS 4.0 base score is 5.1 (medium severity), reflecting network attack vector, low complexity, and partial impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Upgrade MaxKB to version 2.8.0 or later, where this stored XSS vulnerability has been fixed. Since the vendor advisory confirms the fix in 2.8.0, applying this official update is the recommended remediation. No additional mitigations are specified or required beyond upgrading.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-07T00:23:30.596Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69dd9c8b82d89c981fa1192c
Added to database: 4/14/2026, 1:46:51 AM
Last enriched: 4/14/2026, 2:02:01 AM
Last updated: 4/14/2026, 7:25:16 AM
Views: 9
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