diff --git a/.changeset/tender-tigers-shave.md b/.changeset/tender-tigers-shave.md
new file mode 100644
index 00000000..be292d88
--- /dev/null
+++ b/.changeset/tender-tigers-shave.md
@@ -0,0 +1,5 @@
+---
+'@asyncapi/cli': minor
+---
+
+CLI fails for GitHub URLs with slash-based branches and multi-dot spec files
diff --git a/src/domains/models/SpecificationFile.ts b/src/domains/models/SpecificationFile.ts
index a0d19f19..21896d18 100644
--- a/src/domains/models/SpecificationFile.ts
+++ b/src/domains/models/SpecificationFile.ts
@@ -234,7 +234,7 @@ export async function fileExists(name: string): Promise<boolean> {
       return true;
     }
 
-    const extension = name.split('.')[1];
+    const extension = path.extname(name).substring(1);
 
     const allowedExtenstion = ['yml', 'yaml', 'json'];
 
diff --git a/src/domains/services/validation.service.ts b/src/domains/services/validation.service.ts
index 1d0dffcf..4f7eb55b 100644
--- a/src/domains/services/validation.service.ts
+++ b/src/domains/services/validation.service.ts
@@ -68,17 +68,9 @@ const convertGitHubWebUrl = (url: string): string => {
   // Remove fragment from URL before processing
   const urlWithoutFragment = url.split('#')[0];
 
-  // Handle GitHub web URLs like: https://github.com/owner/repo/blob/branch/path
-  // eslint-disable-next-line no-useless-escape
-  const githubWebPattern = /^https:\/\/github\.com\/([^\/]+)\/([^\/]+)\/blob\/([^\/]+)\/(.+)$/;
-  const match = urlWithoutFragment.match(githubWebPattern);
-
-  if (match) {
-    const [, owner, repo, branch, filePath] = match;
-    return `https://api.github.com/repos/${owner}/${repo}/contents/${filePath}?ref=${branch}`;
-  }
-
-  return url;
+  return urlWithoutFragment
+    .replace('github.com', 'raw.githubusercontent.com')
+    .replace('/blob/', '/');
 };
 
 /**