Publish Advisories

GHSA-f69v-xrj8-rhxf GHSA-pmc3-p9hx-jq96
2026-05-22 18:04:22 -07:00 · 2025-04-23 14:45:22 +00:00
parent 30fe542331
commit f03e4b25a3
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+{
+  "schema_version": "1.4.0",
+  "id": "GHSA-pmc3-p9hx-jq96",
+  "modified": "2025-04-23T14:43:44Z",
+  "published": "2025-04-23T14:43:44Z",
+  "aliases": [],
+  "summary": "uTLS ServerHellos are accepted without checking TLS 1.3 downgrade canaries",
+  "details": "### Description\nBefore version 1.7.0, utls did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a utls ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a utls client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because utls did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint utls connections.\n\n### Fix Commit or Pull Request\n\nrefraction-networking/utls#337, specifically refraction-networking/utls@f8892761e2a4d29054264651d3a86fda83bc83f9\n\n### References\n\n- https://github.com/refraction-networking/utls/issues/181",
+  "severity": [
+    {
+      "type": "CVSS_V3",
+      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
+    }
+  ],
+  "affected": [
+    {
+      "package": {
+        "ecosystem": "Go",
+        "name": "github.com/refraction-networking/utls"
+      },
+      "ranges": [
+        {
+          "type": "ECOSYSTEM",
+          "events": [
+            {
+              "introduced": "0"
+            },
+            {
+              "fixed": "1.7.0"
+            }
+          ]
+        }
+      ]
+    }
+  ],
+  "references": [
+    {
+      "type": "WEB",
+      "url": "https://github.com/refraction-networking/utls/security/advisories/GHSA-pmc3-p9hx-jq96"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/refraction-networking/utls/issues/181"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/refraction-networking/utls/pull/337"
+    },
+    {
+      "type": "WEB",
+      "url": "https://github.com/refraction-networking/utls/commit/f8892761e2a4d29054264651d3a86fda83bc83f9"
+    },
+    {
+      "type": "PACKAGE",
+      "url": "https://github.com/refraction-networking/utls"
+    }
+  ],
+  "database_specific": {
+    "cwe_ids": [
+      "CWE-693"
+    ],
+    "severity": "MODERATE",
+    "github_reviewed": true,
+    "github_reviewed_at": "2025-04-23T14:43:44Z",
+    "nvd_published_at": null
+  }
+}