How severe is CVE-2026-45572?

CVE-2026-45572 has a CVSS score of 4.8/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-45572?

CVE-2026-45572 affects the following packages: decidim-core (RubyGems), decidim-core (RubyGems), decidim-core (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2026-45572?

Update decidim-core to 0.30.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45572 is resolved across your whole dependency graph.

How do I detect CVE-2026-45572 in my RubyGems dependencies?

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

How do I mitigate CVE-2026-45572 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2026-45572 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-45572 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-45572?

CVE-2026-45572 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 17th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-45572?

CVE-2026-45572 is classified as Code Injection (CWE-94). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-45572 published, and has it been updated?

CVE-2026-45572 was published on August 6, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

MEDIUM severity

CVE-2026-45572 — decidim-core

MEDIUMFix: decidim/decidim#16451

CVE-2026-45572 is a medium-severity (CVSS 4.8) Code Injection vulnerability in decidim-core. A fix is available for decidim-core — see the affected versions and patch details below.

Decidim: HTML content blocks allow stored script execution

Also known asGHSA-533c-2vh9-4r86

Published

Aug 6, 2026

Updated

Oct 28, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45572.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs17th percentile — riskier than 17% of all scored CVEsHighest risk

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

3 pkgs affected

💎decidim-core💎decidim-core💎decidim-core

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

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.

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.

Patches

See https://github.com/decidim/decidim/pull/16451

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.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`decidim-core`	all versions	0.30.9`bundle update decidim-core --conservative`
💎RubyGems	`decidim-core`	≥ 0.31.0.rc1&&< 0.31.5	0.31.5`bundle update decidim-core --conservative`
💎RubyGems	`decidim-core`	≥ 0.32.0.rc1&&< 0.32.0	0.32.0`bundle update decidim-core --conservative`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for decidim-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update decidim-core to 0.30.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45572 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

## 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. <img width="1541" height="439" alt="decidim-html-xss-01" src="https: