What’s Vulnerable › Vulnerabilities

CVE-2020-5809

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-12-30 · updated 2026-06-17
• Weakness: CWE-79

Description

A stored XSS vulnerability exists in Umbraco CMS <= 8.9.1 or current. An authenticated user can inject arbitrary JavaScript code into iframes when editing content using the TinyMCE rich-text editor, as TinyMCE is configured to allow iframes by default in Umbraco CMS.

Affected products

• Umbraco-CMS: through 8.9.1

References

• https://www.tenable.com/security/research/tra-2020-59
• https://www.tenable.com/security/research/tra-2020-59

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