Lobe Chat affected by Cross-Site Scripting(XSS) that can escalate to Remote Code Execution(RCE)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-23733: 0.15% estimated exploitation activity in the next 30 days; percentile 3.87 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A stored Cross-Site Scripting (XSS) vulnerability in the Mermaid artifact renderer allows attackers to execute arbitrary JavaScript within the application context. This XSS can be escalated to Remote Code Execution (RCE). Details The vulnerability exists in the Renderer component responsible for rendering Mermaid diagrams within chat artifacts. The content variable, which is derived from user or AI-generated messages, is passed directly to the <Mermaid component without any sanitization. The Mermaid library renders HTML labels (e.g., nodes defined with ["..."]) directly into the DOM. If the content contains malicious HTML tags (like <img onerror=...), they are executed. PoC mermaid graph TD; A"<img src=x…

Published by the source

20 Jan 2026, 17:54 UTC

Last modified by the source

5 Feb 2026, 13:48 UTC

Source last checked

26 Oct 2026, 12:42 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4gpc-rhpj-9443

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-4gpc-rhpj-9443

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-4gpc-rhpj-9443

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# Patch Next advisory brief: CVE-2026-23733

Advisory: Lobe Chat affected by Cross-Site Scripting(XSS) that can escalate to Remote Code Execution(RCE)
IDs: CVE-2026-23733, GHSA-4gpc-rhpj-9443
Record: https://patchnext.com/advisories/cve-2026-23733 (revision 3, source checked 26 Oct 2026, 12:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @lobehub/chat: affected <= 1.143.2

## Suggested inspection (read-only)
- `npm ls @lobehub/chat --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @lobehub/chat.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4gpc-rhpj-9443 (GitHub-reviewed advisory GHSA-4gpc-rhpj-9443 lists affected ranges: npm @lobehub/chat >=0 <=1.143.2)
- Verified: https://osv.dev/vulnerability/GHSA-4gpc-rhpj-9443 (OSV record GHSA-4gpc-rhpj-9443 lists affected ranges: npm @lobehub/chat >=0 <=1.143.2)

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