CVE-2026-55220: Pimcore Hotspotimage getDataFromResource() unrestricted Serialize::unserialize over object-store column (PHP Object Injection, CWE-502)

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.7%, percentile 52: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 52% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes pimcore/pimcore (Composer (PHP)) >= 2026.1.0, <= 2026.1.5, fixed in 2026.1.6; pimcore/pimcore (Composer (PHP)) <= 12.3.9, fixed in 12.3.10. Check your lockfile, including transitive dependencies.

What it is

Pimcore is an Open Source Data & Experience Management Platform. Prior to 11.5.19, 12.3.10, and 2026.1.6, Pimcore\Model\DataObject\ClassDefinition\Data\Hotspotimage::getDataFromResource() in models/DataObject/ClassDefinition/Data/Hotspotimage.php passes the field hotspots object-store column to Pimcore\Tool\Serialize::unserialize() without an allowed-classes restriction after JSON decoding fails. An attacker with a separate capability to write crafted PHP serialized bytes into that column can instantiate available classes and trigger magic methods when an affected DataObject is loaded, which can produce arbitrary file writes or code execution through bundled gadget chains. The related ImageGallery, Block, and Video callers use the same fallback pattern, but the identified June fix changes the Hotspotimage caller only. This issue is fixed for Hotspotimage in versions 11.5.19, 12.3.10, and 2026.1.6.

From the GitHub advisory

Summary

Pimcore\Model\DataObject\ClassDefinition\Data\Hotspotimage::getDataFromResource() deserializes the hotspots object-store column through the Pimcore\Tool\Serialize::unserialize() wrapper without a class allowlist (the wrapper's $allowedClasses parameter defaults to true, i.e. fully unrestricted). Because the persistence layer always stores this column as PHP-serialize()d bytes, every load of a DataObject that has a Hotspotimage (advanced image) field runs an unrestricted unserialize() over the stored column value. An attacker who can write the hotspots store column with crafted serialized bytes achieves PHP Object Injection (CWE-502): arbitrary classes are instantiated and their magic methods (wakeup/destruct) execute, which is exploitable for remote code execution via gadget chains present in Pimcore's own bundled dependencies (e.g. guzzlehttp/guzzle).

The same field-data family also affects the sibling marshallers ImageGallery, Block, and Video, which use the identical jsondecode(...) ?: Serialize::unserialize(...) fallback over their respective store columns. The root cause is shared: Serialize::unserialize() defaults to an unrestricted class list, and these callers pass no second argument.

Severity

High. Successful exploitation yields PHP Object Injection leading to remote code execution (proven below as arbitrary file write using a gadget from Pimcore's bundled guzzlehttp/guzzle 7.11.0). This is the deserialization leg of an attack: it requires the ability to write the hotspots object-store column with attacker-chosen serialized bytes. No class-allowlist defense is present, so any such write is directly weaponizable on the next object load. CVSS-wise this is comparable to other deserialization sinks over attacker-influenceable storage in this codebase.

Weakness type: CWE-502.

Product: pimcore/pimcore (Composer (PHP)) · Assigned by: GitHub_M · Published: 2026-08-28

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.68% probability of exploitation activity in the next 30 days; percentile 52.

Timeline

• 2026-08-28 — CVE record published by GitHub_M
• 2026-08-28 — GitHub-reviewed advisory GHSA-w23p-wrp7-ch38 published (critical)
• 2026-08-31 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-w23p-wrp7-ch38 github.com
2. CVE.org record CVE-2026-55220 cve.org
3. NVD entry CVE-2026-55220 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest