CVE-2026-33661 WeChat Pay callback signature verification bypassed when Host header is localhost

Pay is an open-source payment SDK extension package for various Chinese payment services. Prior to version 3.7.20, the verifywechatsign function in src/Functions.php unconditionally skips all signature verification when the PSR-7 request reports localhost as the host. An attacker can exploit this...

User Impersonation

Overview Affected versions of this package are vulnerable to User Impersonation via the verifywechatsign function. An attacker can cause unauthorized order status changes by sending a crafted HTTP request with a Host: localhost header, which bypasses signature verification and allows forging...

WeChat Pay callback signature verification bypassed when Host header is localhost

Summary The verifywechatsign function in src/Functions.php unconditionally skips all signature verification when the PSR-7 request reports localhost as the host. An attacker can exploit this by sending a crafted HTTP request to the WeChat Pay callback endpoint with a Host: localhost header,...