Vulnerability-Lookup

CVE-2026-83627 (GCVE-0-2026-83627)

Vulnerability from cvelistv5 – Published: 2026-09-05 05:30 – Updated: 2026-09-07 11:17

Title

Hummingbird – Speed Optimization, Caching, Minify, Compress & CDN <= 3.21.0 - Unauthenticated Remote Code Execution via Cookie Name in Page Cache Debug Log

Summary

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.

Severity

9.8 (Critical)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-07 11:08 UTC

CWE

CWE-94 - Improper Control of Generation of Code ('Code Injection')

Assigner

Wordfence CNA under the mitre root

CNA scorecard C 65/100 over 2451 records in the last 180 days details

References

8 references

URL	Tags
https://www.wordfence.com/threat-intel/vulnerabil…
https://plugins.trac.wordpress.org/browser/hummin…
https://plugins.trac.wordpress.org/browser/hummin…
https://plugins.trac.wordpress.org/browser/hummin…
https://plugins.trac.wordpress.org/browser/hummin…
https://plugins.trac.wordpress.org/changeset?repo…
https://plugins.trac.wordpress.org/changeset/3675…
https://plugins.trac.wordpress.org/changeset?old_…

Impacted products

1 product

Vendor	Product	Version	CPE status
wpmudev	Hummingbird Performance – Cache & Page Speed Optimization for Core Web Vitals \| Critical CSS \| Minify CSS \| Defer CSS Javascript \| CDN	Affected: 0 , ≤ 3.21.0 (semver)	guessed

Credits

Kuba

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-83627

Vulnerability from fkie_nvd - Published: 2026-09-05 06:17 - Updated: 2026-09-08 13:12

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	security@wordfence.com	https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1973
	security@wordfence.com	https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1982
	security@wordfence.com	https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L749
	security@wordfence.com	https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L752
	security@wordfence.com	https://plugins.trac.wordpress.org/changeset/3675836/hummingbird-performance/trunk/core/modules/class-page-cache.php
	security@wordfence.com	https://plugins.trac.wordpress.org/changeset?old_path=%2Fhummingbird-performance/tags/3.20.0&new_path=%2Fhummingbird-performance/tags/3.21.2
	security@wordfence.com	https://plugins.trac.wordpress.org/changeset?reponame=&new=3675836%40hummingbird-performance%2Ftags%2F3.21.2&old=3614991%40hummingbird-performance%2Ftags%2F3.20.0
	security@wordfence.com	https://www.wordfence.com/threat-intel/vulnerabilities/id/65c3ca36-79e6-47f8-9524-27e7631f4caf?source=cve

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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    {
      "lang": "en",
      "value": "The Hummingbird \u2013 Speed Optimization, Caching, Minify, Compress \u0026 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 \u0027\u003c?php die(); ?\u003e\u0027 header. That header is guarded by class_exists( \u0027Filesystem\u0027 ), 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 \u2014 a state reached by the plugin\u0027s own \u0027Clear logs\u0027 action, any cache flush, or unattended via the plugin\u0027s daily log-rotation cron, which can strip the protective header from an existing log file."
    }
  ],
  "id": "CVE-2026-83627",
  "lastModified": "2026-09-08T13:12:58.310",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "security@wordfence.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-83627",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-07T11:08:44.158463Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-05T06:17:10.080",
  "references": [
    {
      "source": "security@wordfence.com",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1973"
    },
    {
      "source": "security@wordfence.com",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1982"
    },
    {
      "source": "security@wordfence.com",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L749"
    },
    {
      "source": "security@wordfence.com",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L752"
    },
    {
      "source": "security@wordfence.com",
      "url": "https://plugins.trac.wordpress.org/changeset/3675836/hummingbird-performance/trunk/core/modules/class-page-cache.php"
    },
    {
      "source": "security@wordfence.com",
      "url": "https://plugins.trac.wordpress.org/changeset?old_path=%2Fhummingbird-performance/tags/3.20.0\u0026new_path=%2Fhummingbird-performance/tags/3.21.2"
    },
    {
      "source": "security@wordfence.com",
      "url": "https://plugins.trac.wordpress.org/changeset?reponame=\u0026new=3675836%40hummingbird-performance%2Ftags%2F3.21.2\u0026old=3614991%40hummingbird-performance%2Ftags%2F3.20.0"
    },
    {
      "source": "security@wordfence.com",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/65c3ca36-79e6-47f8-9524-27e7631f4caf?source=cve"
    }
  ],
  "sourceIdentifier": "security@wordfence.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-94"
        }
      ],
      "source": "security@wordfence.com",
      "type": "Secondary"
    }
  ]
}

GHSA-4RX5-C9JJ-CFRJ

Vulnerability from github – Published: 2026-09-05 06:32 – Updated: 2026-09-05 06:32

Details

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 '' 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.

Severity

9.8 (Critical)


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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-83627"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-05T06:17:10Z",
    "severity": "CRITICAL"
  },
  "details": "The Hummingbird \u2013 Speed Optimization, Caching, Minify, Compress \u0026 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 \u0027\u003c?php die(); ?\u003e\u0027 header. That header is guarded by class_exists( \u0027Filesystem\u0027 ), 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 \u2014 a state reached by the plugin\u0027s own \u0027Clear logs\u0027 action, any cache flush, or unattended via the plugin\u0027s daily log-rotation cron, which can strip the protective header from an existing log file.",
  "id": "GHSA-4rx5-c9jj-cfrj",
  "modified": "2026-09-05T06:32:38Z",
  "published": "2026-09-05T06:32:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-83627"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1973"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L1982"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L749"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/hummingbird-performance/trunk/core/modules/class-page-cache.php#L752"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/changeset/3675836/hummingbird-performance/trunk/core/modules/class-page-cache.php"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/changeset?old_path=%2Fhummingbird-performance/tags/3.20.0\u0026new_path=%2Fhummingbird-performance/tags/3.21.2"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/changeset?reponame=\u0026new=3675836%40hummingbird-performance%2Ftags%2F3.21.2\u0026old=3614991%40hummingbird-performance%2Ftags%2F3.20.0"
    },
    {
      "type": "WEB",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/65c3ca36-79e6-47f8-9524-27e7631f4caf?source=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-83627 (GCVE-0-2026-83627)

FKIE_CVE-2026-83627

GHSA-4RX5-C9JJ-CFRJ

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Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour