CVE-2026-10721 Concrete CMS: PHP Object Injection via unserialize() calls
Unauthenticated attackers can achieve arbitrary code execution in Concrete CMS by injecting malicious serialized payloads into the database.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-10721?
CVE-2026-10721 is a high-severity unsafe deserialization vulnerability in Concrete CMS, published on 10 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Concrete CMS below 9.5.2 is vulnerable to PHP Object Injection via unserialize() calls in the in Permission, Cache, and Search components. An unauthenticated attacker may trigger arbitrary PHP object instantiation if a malicious serialized payload has been placed in the database. Thanks XananasX7 for reporting.
Weakness: CWE-502
Which versions are affected by CVE-2026-10721?
2 open source packages ship an affected version, including concrete5/concrete5.
| Package | Affected | Fixed in |
|---|---|---|
concrete5/concrete5 Packagist | All versions | 9.5.2 |
concrete5/concrete5 Packagist | All versions | 9.5.2 |
How do I fix CVE-2026-10721?
Upgrade concrete5/concrete5 to 9.5.2 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-10721 being exploited?
There is no known exploitation of CVE-2026-10721 in the wild and no public exploit code.
Sources
Also known as GHSA-g82f-9pw7-773w.