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MEDIUM severity

CVE-2018-17256 — umbraco

MEDIUM

CVE-2018-17256 is a medium-severity (CVSS 4.8) Cross-site Scripting (XSS) vulnerability in umbraco. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Umbraco CMS vulnerable to stored XSS

Also known asGHSA-wrrj-r2j4-969w
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 25, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs51th percentile — riskier than 51% of all scored CVEsHighest risk
0.00%0.38%0.77%1.15%0.4%0.7%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
.NETumbraco

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

Persistent cross-site scripting (XSS) vulnerability in Umbraco CMS 7.12.3 allows authenticated users to inject arbitrary web script via the Header Name of a content (Blog, Content Page, etc.). The vulnerability is exploited when updating or removing public access of a content.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
.NETNuGetumbracoall versionsNo fix

Affected Products

1 product · 1 configurations
Application
umbraco cmsumbraco
1 version
7.12.3

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for umbraco, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    The records we use list no patched version of umbraco for CVE-2018-17256. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Persistent cross-site scripting (XSS) vulnerability in Umbraco CMS 7.12.3 allows authenticated users to inject arbitrary web script via the Header Name of a content (Blog, Content Page, etc.). The vulnerability is exploited when updating or removing public access of a content.
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CVE-2018-17256: umbraco XSS (Medium 4.8)