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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-40757

HIGH · 8.1 CVSS v3.1 Published 2026-06-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
90/100
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
Unauthenticated PHP Object Injection in Château <= 1.2.1 versions.

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

Unauthenticated PHP Object Injection in Château <= 1.2.1 allows remote attackers to inject malicious PHP objects via unserialized user input, potentially leading to remote code execution through magic methods like __destruct() or __wakeup().

MitigationReplace unsafe unserialize() calls with safer alternatives like json_decode() for handling untrusted input, or implement whitelist validation if serialization is required.

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
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/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. Identify Château version
    Locate the version file or header in the Château installation directory. Common locations include version.php, composer.json, or a config header comment.
    Affected if Version is 1.2.1 or lower
  2. Search for unserialize() calls
    Search the PHP source code for unserialize() function calls. Use grep or similar: grep -r "unserialize" /path/to/chateau/
    Affected if The application code contains unserialize() function calls
  3. Trace input to unserialize()
    Examine PHP files that contain unserialize() and trace whether COOKIE, POST, GET, or other user-supplied data is passed directly to it.
    Affected if User-controlled input flows to unserialize() without validation
  4. Verify exposed entry points
    Identify HTTP endpoints, API routes, or forms that accept user input and could trigger the vulnerable unserialize() call.
    Affected if Untrusted input can reach the unserialize() function via web request parameters

Environment is affected if Château version is 1.2.1 or lower AND user-supplied input is passed to PHP's unserialize() function without sanitization.

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

Replace unsafe unserialize() calls with safer alternatives like json_decode() for handling untrusted input, or implement whitelist validation if serialization is required.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2026-40757 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
  • No spam, self-promotion, credentials, or personal data