# CVE-2026-44990: ApostropheCMS sanitize-html XSS bypass via xmp element

Source: https://junglewise.ai/threats/cve-2026-44990-apostrophecms-sanitize-html-xss-bypass-via-xmp-element  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-12. Updated: 2026-06-12  
License: CC BY 4.0 with a link back

CVE-2026-44990 · Severity: critical · CVSS 9.3 · Published 2026-06-12

ApostropheCMS sanitize-html, a library used to clean user-provided web content, contains a flaw that allows malicious code to bypass its security filters. By wrapping malicious scripts in a specific HTML tag, an attacker can trick the system into treating dangerous code as safe text. If this content is then displayed to other users, it could allow attackers to steal session information, hijack accounts, or perform unauthorized actions on the website.

Technologies: [sanitize-html (npm)](https://junglewise.ai/threats/technologies/sanitize-html). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-44990 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44990 being exploited in the wild.

**How severe is CVE-2026-44990?** Critical severity, with a CVSS score of 9.3, published 12 June 2026.

**Which products and versions are affected?** sanitize-html (npm) <= 2.17.3, = 2.17.3, SEMVER:introduced=2.17.3,fixed=2.17.4.

**Is there a fix for CVE-2026-44990?** Yes. sanitize-html (npm): upgrade to 2.17.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44990 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-44990?** Check whether you run sanitize-html (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- sanitize-html (npm): upgrade to 2.17.4 or later

  ```sh
  npm install sanitize-html@2.17.4
  ```


## Technical details

A cross-site scripting (XSS) vulnerability exists in sanitize-html prior to version 2.17.4 due to a sanitizer bypass in the default 'disallowedTagsMode: discard' configuration. The root cause is located in the ontext handler (index.js), which fails to escape text content within 'xmp' tags, appending it directly to the output. While htmlparser2 treats 'xmp' as raw text during input parsing, the library's failure to escape this content upon output allows nested tags (such as <script> or event handlers) to become live markup. An unauthenticated remote attacker can exploit this by submitting specially crafted HTML, leading to stored XSS when the sanitized output is rendered in a browser. The issue is resolved in version 2.17.4.

## Affected products

- ApostropheCMS sanitize-html < 2.17.4

## Identifiers

- CVE-2026-44990
- GHSA-rpr9-rxv7-x643

## Timeline

- 2026-05-13: advisory: GitHub security advisory published by maintainers
- 2026-06-12: disclosed: NVD publication date
- 2026-06-12: patched: Version 2.17.4 released to address the bypass

## References

- [https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-rpr9-rxv7-x643](https://github.com/apostrophecms/apostrophe/security/advisories/GHSA-rpr9-rxv7-x643)

## Related threats

- [sanitize-html incomplete : meta refresh URL scheme bypass](https://junglewise.ai/threats/cve-2026-113661-apostrophecms-incomplete-meta-http-equiv-refresh-content-still)
- [ApostropheCMS sanitize-html: SMIL animation namespace-prefix bypass allows javascript: URI injection (XSS)](https://junglewise.ai/threats/cve-2026-113657-apostrophecms-is-an-open-source-node-js-content-management)
- [sanitize-html noscript XSS bypass](https://junglewise.ai/threats/cve-2026-113654-apostrophecms-is-an-open-source-node-js-content-management)
- [sanitize-html unbounded recursion denial of service](https://junglewise.ai/threats/cve-2026-113650-apostrophecms-is-an-open-source-node-js-content-management)
- [sanitize-html stored XSS via SVG SMIL URI-list scheme bypass](https://junglewise.ai/threats/cve-2026-84371-sanitize-html-stored-xss-via-svg-smil-uri-list-scheme-bypass)