# CVE-2026-81753: Flowintel stored XSS in Mermaid note rendering

Source: https://junglewise.ai/threats/cve-2026-81753-flowintel-stored-xss-in-mermaid-note-rendering  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-27. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-81753 · Severity: info · CVSS 6.5 · Published 2026-08-27

Flowintel is a case management and intelligence analysis platform. A stored cross-site scripting vulnerability in the note rendering feature allows an authenticated user to inject malicious JavaScript code into case notes by crafting a specially formatted Mermaid diagram. When other users view the affected case note, the injected JavaScript executes in their browser, potentially allowing an attacker to steal session tokens, modify data, or perform actions on behalf of the victim.

Technologies: [FlowIntel](https://junglewise.ai/threats/technologies/flowintel). Vendors: [FlowIntel](https://junglewise.ai/threats/vendors/flowintel).

## Quick answers

**Is CVE-2026-81753 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-81753 being exploited in the wild.

**How severe is CVE-2026-81753?** Informational severity, with a CVSS score of 6.5, published 27 August 2026.

**Which products and versions are affected?** FlowIntel 3.3.0 and later.

**Is there a fix for CVE-2026-81753?** A patch was published on 2026-08-27: Fix committed on GitHub; patch adds HTML escaping and moves wrapping logic earlier in initialization Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-81753 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-81753?** Check whether you run FlowIntel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A stored XSS vulnerability exists in Flowintel's Mermaid diagram rendering within case notes. The vulnerability stems from insufficient HTML escaping of attacker-controlled markup in Mermaid blocks before they are persisted and rendered to other users. An authenticated user with permission to create or edit notes can inject a crafted Mermaid payload that bypasses sanitization, resulting in arbitrary JavaScript execution when another user views the case note. The attack is persistent because the malicious payload is stored in the database and executed every time the note is accessed. The patch adds explicit Mermaid detection and HTML escaping around token content before rendering, and moves the wrapping logic earlier in page initialization for consistent protection across all Markdown instances.

## Affected products

- Flowintel Flowintel 3.3.0 and later

## Timeline

- 2026-08-27: disclosed
- 2026-08-27: patched: Fix committed on GitHub; patch adds HTML escaping and moves wrapping logic earlier in initialization

## References

- [https://github.com/flowintel/flowintel/commit/61c97e67f5d04030f26e7900c470b52f9f37da06](https://github.com/flowintel/flowintel/commit/61c97e67f5d04030f26e7900c470b52f9f37da06)

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