Critical Vulnerability in Hummingbird WordPress Plugin: Early Warning
- Severity
- CRITICAL
- CVSS
- 9.8
- Affected component
- hummingbird-speed-optimization (wordpress)
- Patched version
- Not yet available
The Hummingbird WordPress plugin, versions up to and including 3.21.0, is reportedly vulnerable to Remote Code Execution. This allows unauthenticated attackers to execute arbitrary PHP code.
What happened
An early warning has been issued for a critical vulnerability in the Hummingbird WordPress plugin. The vulnerability, tracked as CVE-2026-83627, allows unauthenticated attackers to execute arbitrary PHP code by writing to a web-accessible log file. This vulnerability affects all versions up to and including 3.21.0.
The vulnerability was first flagged on September 5, 2026. It has a CVSS score of 9.8, indicating a critical severity level. The plugin in question is used for speed optimization, caching, minification, compression, and CDN integration in WordPress sites.
What to do about it
- Upgrade the Hummingbird plugin to a version beyond 3.21.0.
- Ensure the Page Caching with Debug Log option is disabled if it is not needed.
- Monitor the primary sources for updates on the vulnerability and any official fixes.
How 0Day would have caught this
hummingbird-speed-optimization is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.
Frequently asked questions
Am I affected?
You are affected if you are using the Hummingbird WordPress plugin version 3.21.0 or earlier.
What should I do right now?
Upgrade the Hummingbird plugin to a version beyond 3.21.0 and ensure the Page Caching with Debug Log option is disabled if not needed.
Is there an official fix available?
No official fix has been published yet. Monitor the primary sources for updates.