CVE-2026-81753 PUBLISHED

Flowintel Stored XSS in Case Notes via Malicious Mermaid Diagram Content

Assigner: CIRCL
Reserved: 27.08.2026 Published: 27.08.2026 Updated: 27.08.2026

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

Metrics

CVSS 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
CVSS Score: 5.1

Product Status

Vendor flowintel
Product flowintel
Versions Default: unaffected
  • affected from 0 to 3.3.0 (incl.)

Credits

  • Jeroen Pinoy finder
  • David Cruciani remediation developer

References

Problem Types

  • CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') CWE

Impacts

  • CAPEC-63 Cross-Site Scripting (XSS)