Arbitrary Code Injection Affecting mermaid package, versions <10.9.8>=11.0.0-alpha.1 <11.16.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published8 Aug 2026
- disclosed6 Aug 2026
- credith3ri0s
Introduced: 6 Aug 2026
NewCVE-2026-50159 (opens in a new tab)How to fix?
Upgrade mermaid to version 10.9.8, 11.16.1 or higher.
Overview
mermaid is a package for generation of diagrams and flowcharts from text in a similar manner as markdown.
Affected versions of this package are vulnerable to Arbitrary Code Injection via the CSS namespacing process. An attacker can manipulate the appearance or behavior of adjacent DOM elements by injecting crafted CSS selectors into diagram source content. This is only exploitable if the rendered SVG is not the only child of its parent element, such as when the SVG is manually inserted alongside other elements.
Workaround
This vulnerability can be mitigated by wrapping the SVG in a container element with no other children, or by using configuration options such as setting the securityLevel to 'sandbox' or enabling the 'secure' config value to restrict diagram modifications.