CVE-2026-71981 Cypht < 2.12.2 PHP Object Injection RCE via back_query Parameter
Authenticated attackers can achieve remote code execution by injecting a crafted PHP object into the back_query parameter of the logout handler.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-71981?
CVE-2026-71981 is a high-severity unsafe deserialization vulnerability in cypht-org cypht, published on 1 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Cypht before 2.12.2 contains a PHP object injection vulnerability that allows authenticated attackers to execute arbitrary operating system commands by supplying a crafted PHP object graph in the back_query GET parameter of the logout handler. Attackers can pass a base64-encoded serialized payload through this parameter, which is decoded and passed directly to unserialize() without an allow-list, signature check, or type restriction, enabling gadget-chain exploitation to achieve remote code execution as the web server process.
Weakness: CWE-502
Which versions are affected by CVE-2026-71981?
How do I fix CVE-2026-71981?
No fix has been published for CVE-2026-71981 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-2026-71981 being exploited?
There is no known exploitation of CVE-2026-71981 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-46j6-w3hw-4r9x.