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CVE-2026-33661

Yansongda Pay authentication bypass

8.6 HIGHPublic exploitEPSS 0.67%
  1. Published26 Mar 2026

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 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityNone
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

Affected products

Yansongda Pay< 3.7.20

Remediation

Fixed in
Yansongda Pay≥ 3.7.20

References

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Frequently asked

Is CVE-2026-33661 being actively exploited?

CVE-2026-33661 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.67%.

How severe is CVE-2026-33661?

CVE-2026-33661 has a CVSS 3.1 base score of 8.6, rated high. EPSS estimates a 0.67% probability of exploitation.

Which products are affected by CVE-2026-33661?

Affected products include Yansongda Pay.

How do I fix CVE-2026-33661?

Upgrade affected software to a fixed version, for example Yansongda Pay 3.7.20 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-33661 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.