pimcore/pimcore security advisory

CVE-2026-55634: Pimcore Vulnerable to Remote Code Execution via DataObject Class-Definition Field Name

CVE-2026-55634 is a critical-severity remote code execution vulnerability in the PHP package pimcore/pimcore (CVSS 9.9), published 28 August 2026. The advisory does not name a fixed version. Exploiting it needs a low-privilege user account.

critical 9.9 published 2026-08-28 · updated 2026-09-09

Affected versions: <= 12.3.9
>= 2026.1.0, <= 2026.1.5
Fixed in: not stated
Newest release: 2026.3.4
Severity: Critical · CVSS 9.9
Type: Remote code execution
CWE-89, CWE-94
Exploited in the wild: Not on the CISA KEV list
checked 2026-11-04

Is your pimcore/pimcore version affected?

Run composer show pimcore/pimcore in your project, then enter the version. We check it against this and every other known pimcore/pimcore advisory.

Who can exploit CVE-2026-55634

Access: A normal, low-privilege user account in the app.

CVSS vector (scored by GitHub): CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Your app is only exposed if it uses the affected part of pimcore/pimcore. The advisory below says which part that is. If you are not sure, upgrade anyway: it costs less than finding out.

How to fix CVE-2026-55634 in pimcore/pimcore

Find the installed version: composer show pimcore/pimcore. If you never required it yourself, composer why pimcore/pimcore shows which package pulls it in.
Update it: composer update pimcore/pimcore --with-all-dependencies.
If Composer will not go that high, your composer.json constraint is holding it back. Widen it (for example "pimcore/pimcore": "^2026.3.4" if you can take that version), or upgrade the package that requires it.
Run composer audit. It reads the same advisory data and should no longer list CVE-2026-55634.
Commit composer.lock and deploy it. On the server, run composer install --no-dev from the lock file, not composer update.

If you cannot upgrade yet

General hardening for remote code execution issues while the upgrade waits. None of it replaces the fix.

Never pass user-controlled data to unserialize() or to template rendering, and restrict who can edit templates or settings.
Put a web application firewall in front of the app and watch for new PHP files or admin users.
If your app does not use the affected feature, note that in your audit, but still plan the upgrade.

The CVE-2026-55634 advisory

Pimcore is an Open Source Data & Experience Management Platform. Prior to 11.5.19, 12.3.10, and 2026.1.6, the class-definition import endpoint /pimcore-studio/api/class/definition/configuration-view/detail/{id}/import accepts a DataObject field name that is emitted without an identifier allowlist by lib/DataObject/ClassBuilder/FieldDefinitionPropertiesBuilder.php into generated PHP properties and by models/DataObject/ClassDefinition/Helper/Dao.php into ALTER TABLE identifiers. An authenticated user with the objects permission can inject PHP syntax into the generated DataObject class, causing attacker-controlled code in generated var/classes/DataObject/.php files to run when an object of that class is instantiated, and can also inject SQL identifier content into schema-changing statements. The central models/DataObject/ClassDefinition/Data.php::setName() validation did not reject semicolons, braces, backticks, spaces, or other non-identifier characters. This issue is fixed in versions 11.5.19, 12.3.10, and 2026.1.6.

Description from the CVE record, published by GitHub (the CVE Numbering Authority), via the NVD entry for CVE-2026-55634. Advisory title: “Pimcore Vulnerable to Remote Code Execution via DataObject Class-Definition Field Name”.

References

GitHub advisory GHSA-9x44-4gxf-8c25 github.com
GitHub advisory GHSA-r2f4-ff2p-xc64 github.com
Fix commit a4f8c3c github.com
Pull request #19183 github.com
Release v2026.1.6 github.com

Other pimcore/pimcore advisories

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Where this data comes from

Affected and fixed versions: the Packagist security advisories API (GitHub Advisory Database and FriendsOfPHP), the same data composer audit uses. Synced 2026-11-03.
Description, score, weakness and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Exploited-in-the-wild status: the CISA Known Exploited Vulnerabilities catalog, checked 2026-11-04.
Compiled by Daniel Lasek at Laskyr from the sources above. The summary, “who can exploit it”, “how to fix it” and hardening sections are our plain-English reading of the record and are generated from it. The quoted description is the record's own text. Spot an error? Tell us.