Description
The Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 3.21.0 via the log_msg() function in core/modules/class-page-cache.php. The page-cache debug log is written to wp-content/wphb-logs/page-caching-log.php, a directly web-accessible PHP file that is supposed to be protected by a leading '<?php die(); ?>' header. That header is guarded by class_exists( 'Filesystem' ), which can never match because class_exists() resolves string arguments in the global namespace while the class is Hummingbird\Core\Filesystem; when the log is created during a front-end request the header is therefore omitted entirely. get_cookies() then writes the raw name of any cookie matching the wphb_cache_ prefix into that file without sanitization. This makes it possible for unauthenticated attackers to write arbitrary PHP into the log file with a single anonymous request and execute it by requesting the file directly, resulting in full remote code execution. Exploitation requires the site administrator to have enabled Page Caching with the Debug Log option (non-default), and the log file to be created during a front-end request — a state reached by the plugin's own 'Clear logs' action, any cache flush, or unattended via the plugin's daily log-rotation cron, which can strip the protective header from an existing log file.
Published: 2026-09-05
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Mon, 07 Sep 2026 12:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Mon, 07 Sep 2026 08:45:00 +0000

Type Values Removed Values Added
First Time appeared Wordpress
Wordpress wordpress
Wpmudev
Wpmudev hummingbird Performance – Cache & Page Speed Optimization For Core Web Vitals | Critical Css | Minify Css | Defer Css Javascript | Cdn
Vendors & Products Wordpress
Wordpress wordpress
Wpmudev
Wpmudev hummingbird Performance – Cache & Page Speed Optimization For Core Web Vitals | Critical Css | Minify Css | Defer Css Javascript | Cdn

Sat, 05 Sep 2026 05:45:00 +0000

Type Values Removed Values Added
Description The Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 3.21.0 via the log_msg() function in core/modules/class-page-cache.php. The page-cache debug log is written to wp-content/wphb-logs/page-caching-log.php, a directly web-accessible PHP file that is supposed to be protected by a leading '<?php die(); ?>' header. That header is guarded by class_exists( 'Filesystem' ), which can never match because class_exists() resolves string arguments in the global namespace while the class is Hummingbird\Core\Filesystem; when the log is created during a front-end request the header is therefore omitted entirely. get_cookies() then writes the raw name of any cookie matching the wphb_cache_ prefix into that file without sanitization. This makes it possible for unauthenticated attackers to write arbitrary PHP into the log file with a single anonymous request and execute it by requesting the file directly, resulting in full remote code execution. Exploitation requires the site administrator to have enabled Page Caching with the Debug Log option (non-default), and the log file to be created during a front-end request — a state reached by the plugin's own 'Clear logs' action, any cache flush, or unattended via the plugin's daily log-rotation cron, which can strip the protective header from an existing log file.
Title Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN <= 3.21.0 - Unauthenticated Remote Code Execution via Cookie Name in Page Cache Debug Log
Weaknesses CWE-94
References
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


Subscriptions

Wordpress Wordpress
Wpmudev Hummingbird Performance – Cache & Page Speed Optimization For Core Web Vitals | Critical Css | Minify Css | Defer Css Javascript | Cdn
cve-icon MITRE

Status: PUBLISHED

Assigner: Wordfence

Published:

Updated: 2026-09-07T11:17:26.770Z

Reserved: 2026-08-31T21:02:35.689Z

Link: CVE-2026-83627

cve-icon Vulnrichment

Updated: 2026-09-07T11:15:17.261Z

cve-icon NVD

Status : Deferred

Published: 2026-09-05T06:17:10.080

Modified: 2026-09-08T13:12:58.310

Link: CVE-2026-83627

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-07T08:25:37Z

Weaknesses