What’s Vulnerable › Vulnerabilities

CVE-2026-118660: Happy DOM: SSRF via iframe and link stylesheet when parsing untrusted HTML

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-28 · updated 2026-10-29
• Weakness: CWE-918

Description

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Prior to 21.0.0, Happy DOM loads iframe src URLs and link rel="stylesheet" href URLs by default while parsing untrusted HTML on the server because disableIframePageLoading and disableCSSFileLoading default to false. An attacker who controls parsed HTML can therefore cause server-side requests to arbitrary internal or cloud endpoints without an application opt-in and may expose confidential responses or credentials returned by those endpoints. This issue is fixed in version 21.0.0.

Affected products

• capricorn86 happy-dom: before 21.0.0

References

• https://github.com/capricorn86/happy-dom/commit/0a99c7525a1d0043e3182843ae33466ab7b19e74
• https://github.com/capricorn86/happy-dom/pull/2502
• https://github.com/capricorn86/happy-dom/releases/tag/v21.0.0
• https://github.com/capricorn86/happy-dom/security/advisories/GHSA-c8p4-j97h-3vg8

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