sanitize-html has incomplete URI scheme validation in that allows javascript: URIs through action, formaction, data, poster, and background attributes

Exploitation

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

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2026-53606: 0.21% estimated exploitation activity in the next 30 days; percentile 11.45 (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.

Summary sanitize-html uses allowedSchemesAppliedToAttributes (default: ['href', 'src', 'cite']) to gate the naughtyHref() function that blocks dangerous URI schemes like javascript: and vbscript:. The HTML specification defines 10+ attributes that accept URIs (action, formaction, data, poster, background, ping, xlink:href, dynsrc, lowsrc), but none of these are included in the default gate list. When a developer allows any of these attributes in their configuration, javascript: URIs pass through completely unmodified, enabling XSS. The library has zero awareness of these URI-bearing attributes — none appear anywhere in the 854-line source file (verified by grep). No warning mechanism exists, and the README provides no security guidance about expanding allowedSchemesAppliedToAttributes when allowing form or media attributes. Severity Exploitation requires non-default configuration: the developer must explicitly allow a non-default tag (e.g., form) AND a non-default attribute (e.g.,…

Published by the source

31 Jul 2026, 21:43 UTC

Last modified by the source

31 Jul 2026, 21:43 UTC

Source last checked

26 Oct 2026, 13:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-vccv-cmxp-4j9h

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# Patch Next advisory brief: CVE-2026-53606

Advisory: sanitize-html has incomplete URI scheme validation in that allows javascript: URIs through action, formaction, data, poster, and background attributes
IDs: CVE-2026-53606, GHSA-vccv-cmxp-4j9h
Record: https://patchnext.com/advisories/cve-2026-53606 (revision 1, source checked 26 Oct 2026, 13:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: sanitize-html 2.17.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm sanitize-html: affected >= 1.18.0, <= 2.17.4; fixed in 2.17.5

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on sanitize-html.
- 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://github.com/advisories/GHSA-vccv-cmxp-4j9h (GitHub-reviewed advisory GHSA-vccv-cmxp-4j9h lists affected ranges: npm sanitize-html >=1.18.0 <=2.17.4)

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