CVE-2026-67399 Deserialization in WHMCS
Remote attackers can execute arbitrary code via unsafe deserialization in WHMCS, requiring immediate upgrades to patched versions.
- 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-2026-67399?
CVE-2026-67399 is a critical unsafe deserialization vulnerability in WebPros WHMCS, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Deserialization of untrusted data in WHMCS 9.0.0 before 9.0.8 and 8.0.0 before 8.13.7 allows remote attackers to execute arbitrary code.
Weakness: CWE-502
Which versions are affected by CVE-2026-67399?
How do I fix CVE-2026-67399?
No fix has been published for CVE-2026-67399 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-2026-67399 being exploited?
There is no known exploitation of CVE-2026-67399 in the wild and no public exploit code.
Sources
Also known as GHSA-5jq9-2qvc-rc4h.