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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2025-39500

CRITICAL · 9.8 CVSS v3.1 Published 2025-05-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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
Deserialization of Untrusted Data vulnerability in GoodLayers Goodlayers Hostel gdlr-hostel allows Object Injection.This issue affects Goodlayers Hostel: from n/a through <= 3.1.2.

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 · moderate confidence

A PHP Object Injection vulnerability exists in the GoodLayers Hostel plugin (gdlr-hostel) where untrusted data is deserialized without proper validation. This allows remote attackers to inject arbitrary PHP objects potentially leading to remote code execution if suitable gadget chains exist in the application or installed plugins.

MitigationUpdate to a patched version if available; otherwise disable the plugin until a fix is released. If immediate remediation is required, audit the codebase for unsafe unserialize() calls and implement whitelisting or JSON-based serialization.

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
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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. Confirm gdlr-hostel plugin is installed
    Check the WordPress plugins directory for the gdlr-hostel plugin folder, or list all installed plugins via wp-cli: wp plugin list --status=active --format=csv
    Affected if The gdlr-hostel plugin folder exists in wp-content/plugins/ or appears in the active plugins list
  2. Identify the installed plugin version
    Check the main plugin PHP file (usually gdlr-hostel.php or index.php) for the Version header in the plugin comment block, or use: grep -i 'Version:' wp-content/plugins/gdlr-hostel/*.php
    Affected if The version cannot be determined or is older than any patched version released after the CVE disclosure date
  3. Locate unsafe unserialize() calls in the plugin
    Search the plugin source code for unserialize() function calls without prior validation: grep -rn 'unserialize' wp-content/plugins/gdlr-hostel/
    Affected if Any unserialize() call is found that processes untrusted input (e.g., $_POST, $_GET, $_COOKIE, or database fields) without sanitization
  4. Identify input sources feeding unserialize()
    Review each unserialize() call found and trace back the data source - check if it receives data from request parameters, user-controlled database fields, or external API responses
    Affected if The unserialize() call receives data directly from $_REQUEST, $_POST, $_GET, or similar user-controlled sources without validation
  5. Verify the vulnerable endpoint is accessible
    If the unserialize() call is within a specific PHP file or AJAX handler, confirm that file is accessible via web requests (check for does_plugin_header_checks or is_admin restrictions in the code)
    Affected if The vulnerable unserialize() code runs in a non-admin context accessible to unauthenticated users
  6. Check for gadget chain availability
    Review installed plugins for known PHP object injection gadget chains (common in popular plugins like WooCommerce, Yoast, etc.) - grep for __wakeup, __destruct, or __toString methods in other active plugins
    Affected if Multiple plugins with magic methods are active, increasing the likelihood of a viable gadget chain for RCE

You are affected if the gdlr-hostel plugin is active and contains unserialize() calls processing untrusted input without validation - update or disable the plugin immediately.

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 if available; otherwise disable the plugin until a fix is released. If immediate remediation is required, audit the codebase for unsafe unserialize() calls and implement whitelisting or JSON-based serialization.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2025-39500 in production — separate from our analysis above.

No notes yet

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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
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