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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2025-26873

CRITICAL · 9.0 CVSS v3.1 Published 2025-03-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
99/100
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 shinetheme Traveler traveler.This issue affects Traveler: from n/a through < 3.2.1.

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 deserialization of untrusted data vulnerability exists in the shinetheme Traveler WordPress theme. The vulnerability allows attackers to potentially execute arbitrary code by injecting malicious serialized PHP objects through user-controlled input that gets passed to unsafe unserialize() calls. This affects all versions prior to 3.2.1.

MitigationUpgrade the Traveler theme to version 3.2.1 or later. If immediate upgrade is not possible, audit the codebase for unsafe unserialize() calls on any user-supplied data (POST, GET, cookies, database fields) and replace with safe alternatives like json_decode().

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
High
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/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. Identify Traveler theme version
    Locate the theme's style.css file in wp-content/themes/traveler/ and look for the 'Version:' header in the file comments, or check the $theme_version variable in the theme's functions.php
    Affected if The reported version is lower than 3.2.1 (e.g., 3.2.0, 3.1.x, 3.0.x, etc.)
  2. Locate unsafe unserialize() calls
    Search the Traveler theme directory for PHP files containing 'unserialize(' using grep or a code search tool: grep -r 'unserialize(' wp-content/themes/traveler/
    Affected if Any unserialize() calls exist in the theme code, particularly in files handling form submissions, AJAX requests, or API endpoints
  3. Trace user input to unserialize
    Examine the unserialize() calls found and inspect whether they receive data from $_POST, $_GET, $_COOKIE, or database fields. Look for patterns like unserialize($_POST['...']), unserialize($_REQUEST['...']), or unserialize($row['field'])
    Affected if User-supplied data from HTTP request parameters or database records is passed directly to unserialize() without sanitization
  4. Verify theme is active on WordPress site
    Check the site's active theme via WordPress admin under Appearance > Themes, or inspect wp_options table for 'template' or 'stylesheet' option values containing 'traveler'
    Affected if The Traveler theme is installed and active, meaning the vulnerable code executes when the site processes requests

A user is affected if the Traveler theme version is below 3.2.1 AND the theme code contains unserialize() calls that process user-controlled input from HTTP requests or database fields.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade the Traveler theme to version 3.2.1 or later. If immediate upgrade is not possible, audit the codebase for unsafe unserialize() calls on any user-supplied data (POST, GET, cookies, database fields) and replace with safe alternatives like json_decode().

Recommended fix Moderate confidence

Traveler theme version 3.2.1 or later

  1. 1. Backup your WordPress site and database before making any changes
  2. 2. Navigate to your WordPress admin dashboard
  3. 3. Go to Appearance > Themes
  4. 4. Locate the Traveler theme
  5. 5. If an update is available, click 'Update Now' to upgrade to version 3.2.1 or later
  6. 6. Alternatively, download the latest version of Traveler theme (3.2.1 or higher) from the official shinetheme marketplace or your purchase source
  7. 7. Upload and install the new version via WordPress theme uploader
  8. 8. Verify the update was successful by checking the theme version in Appearance > Themes
Caveat Review theme changelog/release notes before upgrading, as custom child themes or functionality relying on older internal APIs may require adjustments

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,800
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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-2025-26873 in production — separate from our analysis above.

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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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