CVE-2026-81753 Flowintel Stored XSS in Case Notes via Malicious Mermaid Diagram Content
Attackers can execute JavaScript in other users' browsers by storing malicious Mermaid diagrams in case notes, potentially leading to account takeover.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-81753?
CVE-2026-81753 is a medium-severity cross-site scripting vulnerability in flowintel, published on 27 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Affected versions of Flowintel render Mermaid blocks contained in stored case notes without sufficiently neutralizing attacker-controlled markup. Because Mermaid note content is persisted and later rendered for other users, an attacker with permission to create or edit a note could store a crafted Mermaid payload that results in JavaScript execution when another user views the affected case note.
The patch adds explicit Mermaid detection and HTML escaping around the token content before the generated Mermaid wrapper is returned. It also moves the wrapping logic earlier in page initialization so Markdown instances are protected consistently.
Version impacted >= 3.3.0
Weakness: CWE-79
Which versions are affected by CVE-2026-81753?
How do I fix CVE-2026-81753?
No fix has been published for CVE-2026-81753 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-81753 being exploited?
There is no known exploitation of CVE-2026-81753 in the wild and no public exploit code.
Sources
Also known as GHSA-4xww-rqhr-67w2.