CVE-2026-55573 e107: Unsafe deserialization in install.php allows unauthenticated RCE via POP chain
Unauthenticated attackers can achieve remote code execution on e107 CMS servers by exploiting unsafe deserialization in the installer script.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55573?
CVE-2026-55573 is a critical unsafe deserialization vulnerability in e107inc e107, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
e107 is a content management system (CMS). Prior to 2.3.7, install.php decodes the attacker-controlled previous_steps POST parameter and passes it to unserialize() at file scope and again in the e_install constructor without restricting allowed classes. The installer remains accessible after a normal installation, and a crafted object graph using the bundled GuzzleHttp\Psr7\PumpStream class can flow through paths.hash into site_path, where string coercion invokes an attacker-controlled callable. An unauthenticated attacker who can reach install.php can therefore execute arbitrary PHP functions with the web server process's privileges, leading to full server compromise. This issue is fixed in version 2.3.7.
Weakness: CWE-502
Which versions are affected by CVE-2026-55573?
How do I fix CVE-2026-55573?
No fix has been published for CVE-2026-55573 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-55573 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55573 exists.
Sources
Also known as GHSA-c8h6-wpj3-4cr8.