CVE-2026-109392: Pimcore through 2026.3.1 Stored XSS via ExternalImage Field Version Preview

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-12 · updated 2026-10-13
Weakness: CWE-79

Description

Pimcore through 2026.3.1 contains a stored cross-site scripting vulnerability that allows authenticated backend users to inject scripts by storing unescaped URLs in ExternalImage fields. Attackers with data object edit permission can store attribute-breaking payloads that execute JavaScript in the admin origin when other users open version preview or diff views.

Affected products

pimcore/pimcore: through 2026.3.1

References

https://github.com/pimcore/admin-ui-classic-bundle/blob/2.3/templates/admin/data_object/data_object/preview_version.html.twig#L198
https://github.com/pimcore/pimcore
https://github.com/pimcore/pimcore/blob/v2026.3.1/models/DataObject/ClassDefinition/Data/ExternalImage.php#L169-L203
https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/rJCbgCKjMe
https://www.vulncheck.com/advisories/pimcore-through-2026.3.1-stored-xss-via-externalimage-field-version-preview

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