Decap CMS Cross Site Scripting (XSS) vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.1 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2025-57520: 0.33% estimated exploitation activity in the next 30 days; percentile 26.78 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Decap CMS through 3.8.3 is vulnerable to stored Cross-Site Scripting (XSS) in the admin preview pane. User-controlled fields (e.g., title, description, tags, and body) are rendered in the preview without sufficient sanitization/escaping. An attacker with low-privilege author/contributor access can persist a JavaScript payload in content; when a maintainer or reviewer opens the preview, the payload executes in the CMS admin origin, enabling token/session theft or the execution of privileged actions via the DOM. The issue affects multiple input vectors and requires only passive interaction from the previewing user. As no patched version is available, administrators should restrict untrusted contributor roles and filter or disable preview rendering of untrusted HTML.

Published by the source

10 Sep 2025, 18:30 UTC

Last modified by the source

23 Sep 2025, 20:24 UTC

Source last checked

26 Oct 2026, 12:38 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xp8g-32qh-mv28

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xp8g-32qh-mv28

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# Patch Next advisory brief: CVE-2025-57520

Advisory: Decap CMS Cross Site Scripting (XSS) vulnerability
IDs: CVE-2025-57520, GHSA-xp8g-32qh-mv28
Record: https://patchnext.com/advisories/cve-2025-57520 (revision 3, source checked 26 Oct 2026, 12:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm decap-cms: affected <= 3.8.3

## Suggested inspection (read-only)
- `npm ls decap-cms --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on decap-cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-xp8g-32qh-mv28 (OSV record GHSA-xp8g-32qh-mv28 lists affected ranges: npm decap-cms >=0 <=3.8.3)
- Verified: https://github.com/advisories/GHSA-xp8g-32qh-mv28 (GitHub-reviewed advisory GHSA-xp8g-32qh-mv28 lists affected ranges: npm decap-cms >=0 <=3.8.3)

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