WeChat Pay callback signature verification bypassed when Host header is localhost

MITRE NVD CVE.ORG Print: PDF PDF

Summary

CVECVE-2026-33661
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-26 22:16:29 UTC
Updated2026-04-01 13:47:23 UTC
DescriptionPay 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

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

EPSS: 0.001700000 probability, percentile 0.381250000 (date 2026-04-01)

Problem Types: CWE-290 | CWE-290 CWE-290: Authentication Bypass by Spoofing

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1[email protected]Secondary8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
3.1CNADECLARED8.6HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Yansongda Pay All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Yansongda Pay affected < 3.7.20 Not specified

References

ReferenceSourceLinkTags
github.com/yansongda/pay/commit/26987ebf789f1e7f0a85febb640986ab4289fd7f [email protected] github.com Patch
github.com/yansongda/pay/releases/tag/v3.7.20 [email protected] github.com Release Notes
github.com/yansongda/pay/security/advisories/GHSA-q938-ghwv-8gvc 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Exploit, Vendor Advisory
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