CVE-2026-33661

8.6 HIGH
Published: March 26, 2026 Modified: April 01, 2026
View on NVD

Description

Pay is an open-source payment SDK extension package for various Chinese payment services. Prior to version 3.7.20, the `verify_wechat_sign()` 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, bypassing the RSA signature check entirely. This allows forging fake WeChat Pay payment success notifications, potentially causing applications to mark orders as paid without actual payment. Version 3.7.20 fixes the issue.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/yansongda/pay/releases/tag/v3.7.20
Source: security-advisories@github.com
Release Notes
https://github.com/yansongda/pay/security/advisories/GHSA-q938-ghwv-8gvc
Source: security-advisories@github.com
Exploit Vendor Advisory
https://github.com/yansongda/pay/security/advisories/GHSA-q938-ghwv-8gvc
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Vendor Advisory

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
8.6 / 10.0
EPSS (Exploit Probability)
0.1%
26th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

yansongda