# CVE-2026-109990: Cross-site scripting in Flying Scripts: Delay JavaScript to Improve Site Speed & Performance

> Unauthenticated attackers can inject arbitrary web scripts via comment content, leading to stored XSS execution when users view affected pages.

- **Severity:** High 7.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-x96v-mfm7-f4rv

## What is CVE-2026-109990?

CVE-2026-109990 is a high-severity cross-site scripting vulnerability in gijo Flying Scripts: Delay JavaScript to Improve Site Speed & Performance, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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 <abbr title> attribute and <code> text content — and the XSS is introduced post-save when the plugin's output-buffer rewriter substitutes a double-quote-bearing <code> body into the <abbr title> attribute via predictable, unsalted ___noise___ placeholder keys.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-109990?


## How do I fix CVE-2026-109990?

No fix has been published for CVE-2026-109990 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-109990 being exploited?

There is no known exploitation of CVE-2026-109990 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-109990 and fix it if it is affected.

What it is: CVE-2026-109990 is a high-severity cross-site scripting vulnerability in gijo Flying Scripts: Delay JavaScript to Improve Site Speed & Performance, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-109990 in the wild and no public exploit code.

Affected product: gijo Flying Scripts: Delay JavaScript to Improve Site Speed & Performance. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-109990/ (Markdown: https://insights.sbomify.com/CVE-2026-109990/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-109990
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-109990
- OSV: https://osv.dev/vulnerability/CVE-2026-109990

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-109990/
Summaries are generated and may contain mistakes; the official description above is the record.