CVE-2020-5809
Umbraco CMS vulnerable to stored XSS
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2020-5809- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 3.5 Low
AV:N/AC:M/Au:S/C:N/I:P/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2020-5809- Updated
- 2026-11-02
EUVDEUVD-2022-3294 No score
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.
- Record
EUVD-2022-3294- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-95qr-67rx-9pgh
Umbraco CMS vulnerable to stored XSS
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.
- Record
GHSA-95qr-67rx-9pgh- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2020-5809- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-95qr-67rx-9pgh
Umbraco CMS vulnerable to stored XSS
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.
- Record
GHSA-95qr-67rx-9pgh- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
UmbracoCms.CoreNuGet |
through 8.9.1 | None known |
UmbracoCms.CoreNuGet |
through 8.9.1, plus listed versions 4.10.04.10.0-beta4.10.0-rc4.10.14.11.0 Show 45 moreShow less4.11.14.11.104.11.24.11.2.14.11.2.24.11.2.34.11.34.11.3.14.11.44.11.54.11.64.11.74.11.84.11.94.7.24.8.04.8.0-beta4.8.14.9.04.9.16.0.06.0.0-RC6.0.0-beta6.0.16.0.26.0.36.0.46.0.56.0.66.0.76.0.7.16.1.06.1.0-beta6.1.0-beta-26.1.16.1.26.1.2.16.1.2.26.1.36.1.46.1.56.1.66.2.06.2.0-RC6.2.0.1-RC |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, products | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-5809 is a medium vulnerability (CVSS 5.4) in Umbraco Cms, published December 30, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.69%, the 52nd percentile. No source names a fixed version.
References
Left out here: 213 versions. The JSON record has them.