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Vulnerability record · CVE-2026-33661 · published 26 March 2026

CVE-2026-33661: Yansongda pay authentication bypass by spoofing vulnerability

Yansongda · Pay

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.

7.5 CVSS 3.1 High EPSS 0.67% · top 50.0% CWE-290 · Authentication bypass by spoofing
7.5CVSS 3.1 base score
0.67%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by 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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/yansongda/pay/commit/26987ebf789f1e7f0a85febb640986ab4289fd7f Patch
https://github.com/yansongda/pay/releases/tag/v3.7.20 Release Notes
https://github.com/yansongda/pay/security/advisories/GHSA-q938-ghwv-8gvc ExploitVendor Advisory
https://github.com/yansongda/pay/security/advisories/GHSA-q938-ghwv-8gvc ExploitVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-33661), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.