Is CVE-2021-35513 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2021-35513 being exploited in the wild.

How severe is CVE-2021-35513?

Low severity, with a CVSS score of 3.1, published 10 December 2021.

Which products and versions are affected?

mermaid (npm) SEMVER:introduced=0,fixed=8.11.0.

Is there a fix for CVE-2021-35513?

Yes. mermaid (npm): upgrade to 8.11.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2021-35513 attacked?

It is attacked over the network.

Am I affected by CVE-2021-35513?

Check whether you run mermaid (npm) 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.

CVE-2021-35513: Mermaid cross-site scripting in antiscript feature

CVE-2021-35513 · Severity: low · CVSS 3.1 · Published 2021-12-10

Mermaid is a JavaScript library used to create diagrams and flowcharts from text descriptions. The antiscript security feature, which is meant to block malicious JavaScript code, fails to properly sanitize javascript: URLs, allowing attackers to inject arbitrary JavaScript that executes in users' browsers. This could enable credential theft, session hijacking, or malware distribution to anyone viewing a diagram created by an attacker.

Technologies: mermaid (npm). Vendors: npm.

Quick answers

Is CVE-2021-35513 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2021-35513 being exploited in the wild.
How severe is CVE-2021-35513?: Low severity, with a CVSS score of 3.1, published 10 December 2021.
Which products and versions are affected?: mermaid (npm) SEMVER:introduced=0,fixed=8.11.0.
Is there a fix for CVE-2021-35513?: Yes. mermaid (npm): upgrade to 8.11.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2021-35513 attacked?: It is attacked over the network.
Am I affected by CVE-2021-35513?: Check whether you run mermaid (npm) 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.

How to fix

mermaid (npm): upgrade to 8.11.0 or later
```
npm install mermaid@8.11.0
```

Technical details

Mermaid is a diagram rendering library for web applications. The vulnerability is a stored/reflected XSS flaw in the antiscript option, which claims to block malicious script content. The root cause is inadequate sanitization of javascript: URLs in diagram elements (such as links in SVG nodes). An attacker can craft a malicious diagram definition containing javascript: protocol URLs that execute arbitrary JavaScript when a user views the rendered diagram in a browser. No authentication is required; the attack vector is network-based and requires user interaction (opening/viewing the diagram). The vulnerability was patched in version 8.11.0, which adds proper filtering of javascript: URLs when antiscript mode is enabled. The fix involves stripping javascript: protocol handlers before rendering diagram elements.

Affected products

mermaid-js mermaid before 8.11.0

Identifiers

CVE-2021-35513
GHSA-4f6x-49g2-99fm

Timeline

2021-06-27: disclosed: Vulnerability reported and discussed in GitHub issue #2122
2021-06-27: patched: Fix merged in PR #2123
2021-12-10: advisory: GitHub Security Advisory GHSA-4f6x-49g2-99fm published

References

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