dbcve.org
Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-5217

HIGH · 7.2 CVSS v3.1 Published 2026-04-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
81/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Optimole WordPress plugin suffers from a stored XSS vulnerability in its REST API endpoint. Unauthenticated attackers can inject malicious JavaScript via the 's' parameter (srcset descriptor) because the plugin uses sanitize_text_field() which doesn't escape double quotes, and the stored value is later output in tag_replacer.php without proper escaping into the srcset attribute.

MitigationUpdate to a patched version when available. In the interim, disable the plugin or restrict access to the /wp-json/optimole/ endpoint via firewall rules. After patching, audit existing transients/options for poisoned values.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Optimole plugin is installed
    In WordPress admin, go to Plugins > Installed Plugins and look for 'Optimole' or check wp-content/plugins/ directory for the optimole folder. Check the plugin version in the plugin header.
    Affected if The plugin is not installed or not active.
  2. Identify the installed Optimole version
    In WordPress admin > Plugins, click on Optimole to view details and note the version number. Alternatively, read the 'readme.txt' or 'optimole.php' file header in wp-content/plugins/optimole/.
    Affected if Unable to determine version or version is prior to any patched release.
  3. Confirm REST API endpoint accessibility
    Send a GET request to /wp-json/optimole/ (e.g., curl https://yourdomain.com/wp-json/optimole/). No authentication should be required for the check.
    Affected if The endpoint returns a valid JSON response, indicating it is accessible.
  4. Inspect the vulnerable code pattern
    Examine the file wp-content/plugins/optimole/includes/tag_replacer.php (or equivalent) for the 's' parameter handling. Look for sanitize_text_field() applied to the srcset descriptor without subsequent htmlspecialchars() or esc_attr() escaping before output into the srcset attribute.
    Affected if The code uses sanitize_text_field() on the 's' parameter without proper escaping before outputting into a srcset attribute.

The environment is affected if Optimole is installed, the REST API endpoint is accessible, and the plugin version has not been patched to escape the 's' parameter in srcset output.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update to a patched version when available. In the interim, disable the plugin or restrict access to the /wp-json/optimole/ endpoint via firewall rules. After patching, audit existing transients/options for poisoned values.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,920
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,072.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-5217 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-5217 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data