Summary
Decidim: HTML content blocks allow stored script execution
Description
A privileged admin user who can edit an affected landing page can store arbitrary HTML/JavaScript in an HTML block, and the public page renders it with html_safe and no output escaping.
Technical description
This issue lets any admin who can edit an affected landing page store arbitrary HTML and JavaScript in an HTML block. The block is then rendered back through Decidim::ContentBlocks::HtmlCell#html_content without a sanitization boundary, so the script executes later in visitor's browsers.
Workarounds
Do not give admin permissions to non-trustful users.
Reference
Stored XSS
Credits
This issue was discovered in a security audit organized by the Decidim Association and made by Radically Open Security against Decidim financed by NGI.
Impact
- A user with landing-page editing rights for an affected scope can persist JavaScript that executes in visitor's browsers on that page.
- Because exploitation already requires privileged administrative access, the practical risk is lower than a participant-controlled or unauthenticated stored XSS. It still creates a browser-execution primitive in a trusted admin-editable surface.
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
CVE-2026-45572 has a CVSS score of 4.8 (Medium). The vector is network-reachable, high privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.30.9, 0.31.5, 0.32.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-45572? CVE-2026-45572 is a medium-severity code injection vulnerability in decidim-core (rubygems), affecting versions < 0.30.9. It is fixed in 0.30.9, 0.31.5, 0.32.0. Untrusted input is evaluated as executable code within the application's runtime environment.
- How severe is CVE-2026-45572? CVE-2026-45572 has a CVSS score of 4.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of decidim-core are affected by CVE-2026-45572? decidim-core (rubygems) versions < 0.30.9 is affected.
- Is there a fix for CVE-2026-45572? Yes. CVE-2026-45572 is fixed in 0.30.9, 0.31.5, 0.32.0. Upgrade to this version or later.
- Is CVE-2026-45572 exploitable, and should I be worried? Whether CVE-2026-45572 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-45572 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-45572?
- Upgrade
decidim-coreto 0.30.9 or later - Upgrade
decidim-coreto 0.31.5 or later - Upgrade
decidim-coreto 0.32.0 or later
- Upgrade