What is CVE-2021-35513?

CVE-2021-35513 is a medium-severity vulnerability in Mermaid Project, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-06-27.

How severe is CVE-2021-35513?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Mermaid Project

CVE-2021-35513

Mermaid before 8.11.0 allows XSS when the antiscript feature is used.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-06-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.010 (63.4th percentile), scored 2026-11-04.

Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 63.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Mermaid Project

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/mermaid-js/mermaid/issues/2122 (Third Party Advisory)
github.com/mermaid-js/mermaid/pull/2123 (Patch, Third Party Advisory)
github.com/mermaid-js/mermaid/releases/tag/8.11.0-rc2 (Third Party Advisory, Release Notes)

Frequently asked questions

What is CVE-2021-35513?: CVE-2021-35513 is a medium-severity vulnerability in Mermaid Project, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-06-27.
How severe is CVE-2021-35513?: Medium severity. CVSS v3 base score is 6.1 out of 10.