# CVE-2026-5217: Optimole <= 4.2.2 - Unauthenticated Stored Cross-Site Scripting via Srcset Descriptor Parameter

> Unauthenticated attackers can inject arbitrary scripts via the srcset descriptor parameter in the Optimole WordPress plugin, leading to stored XSS.

- **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:** 11 Apr 2026
- **Updated:** 13 Apr 2026
- **Also known as:** GHSA-8g9h-q4wq-r7gp

## What is CVE-2026-5217?

CVE-2026-5217 is a high-severity cross-site scripting vulnerability in Optimole – Optimize Images in Real Time, published on 11 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Optimole – Optimize Images | Convert WebP & AVIF | CDN & Lazy Load | Image Optimization plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 4.2.2. This is due to insufficient input sanitization and output escaping on the user-supplied 's' parameter (srcset descriptor) in the unauthenticated /wp-json/optimole/v1/optimizations REST endpoint. The endpoint validates requests using an HMAC signature and timestamp, but these values are exposed directly in the frontend HTML making them accessible to any visitor. The plugin uses sanitize_text_field() on the descriptor value of rest.php, which strips HTML tags but does not escape double quotes. The poisoned descriptor is then stored via transients (backed by the WordPress options table) and later retrieved and injected verbatim into the srcset attribute of tag_replacer.php without proper escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts into pages that will execute whenever a user accesses the injected page.

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

## Which versions are affected by CVE-2026-5217?


## How do I fix CVE-2026-5217?

No fix has been published for CVE-2026-5217 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5217 being exploited?

There is no known exploitation of CVE-2026-5217 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5217 and fix it if it is affected.

What it is: CVE-2026-5217 is a high-severity cross-site scripting vulnerability in Optimole – Optimize Images in Real Time, published on 11 Apr 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-2026-5217 in the wild and no public exploit code.

Affected product: Optimole – Optimize Images in Real Time. 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-2026-5217/ (Markdown: https://insights.sbomify.com/CVE-2026-5217/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5217
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5217
- OSV: https://osv.dev/vulnerability/CVE-2026-5217

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-5217/
Summaries are generated and may contain mistakes; the official description above is the record.