diff --git a/src/__tests__/scanner.test.ts b/src/__tests__/scanner.test.ts
index ce0baf3..4ab5669 100644
--- a/src/__tests__/scanner.test.ts
+++ b/src/__tests__/scanner.test.ts
@@ -435,6 +435,59 @@ describe('INSECURE_TRANSPORT rule', () => {
   });
 });
 
+// ─── EXPOSED_SECRETS rule ─────────────────────────────────────────────────────
+
+describe('EXPOSED_SECRETS rule', () => {
+  // Synthetic fixtures: each value is assembled from its prefix plus a filler
+  // body so that no contiguous, real-looking credential literal ever appears in
+  // this source file (which would otherwise trip secret-scanning push
+  // protection). The filler still satisfies each pattern's character class and
+  // length requirement.
+  const body = (n: number) => 'a'.repeat(n);
+  const secrets: Array<[string, string]> = [
+    ['legacy OpenAI key', 'sk-' + body(40)],
+    ['OpenAI project key', 'sk-' + 'proj-' + body(40)],
+    ['OpenAI service-account key', 'sk-' + 'svcacct-' + body(40)],
+    ['Anthropic key', 'sk-' + 'ant-' + body(40)],
+    ['GitHub classic PAT', 'ghp' + '_' + body(36)],
+    ['GitHub OAuth token', 'gho' + '_' + body(36)],
+    ['GitHub fine-grained PAT', 'github' + '_pat_' + body(82)],
+    ['AWS access key id', 'AKIA' + 'A'.repeat(16)],
+    ['Google API key', 'AIza' + body(35)],
+    ['Slack bot token', 'xoxb' + '-1234567890-' + body(16)],
+    ['Stripe live key', 'sk' + '_live_' + body(24)],
+    ['password assignment', 'password=' + body(14)],
+  ];
+
+  it.each(secrets)('fires for a %s', (_label, value) => {
+    const config: ParsedMcpConfig = { rawStrings: [value] };
+    const findings = runRuntimeRule(RuleId.EXPOSED_SECRETS, config);
+    expect(findings).toHaveLength(1);
+    expect(findings[0].ruleId).toBe(RuleId.EXPOSED_SECRETS);
+    expect(findings[0].severity).toBe(Severity.CRITICAL);
+  });
+
+  it('does not fire for benign config strings', () => {
+    const config: ParsedMcpConfig = {
+      rawStrings: [
+        'https://secure-mcp.example.com',
+        'bearer',
+        'filesystem:read',
+        // JWT-style bearer token (assembled from parts) — not a known secret
+        // format, must not trigger a false positive.
+        'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9' + '.' + 'c2VjcmV0LXRva2VuLWZvcnR5LXR3by1jaGFycw',
+      ],
+    };
+    const findings = runRuntimeRule(RuleId.EXPOSED_SECRETS, config);
+    expect(findings).toHaveLength(0);
+  });
+
+  it('does not fire when rawStrings is absent', () => {
+    const findings = runRuntimeRule(RuleId.EXPOSED_SECRETS, {});
+    expect(findings).toHaveLength(0);
+  });
+});
+
 // ─── failOn behaviour ─────────────────────────────────────────────────────────
 
 describe('failOn config', () => {
diff --git a/src/rules/runtime-rules.ts b/src/rules/runtime-rules.ts
index 0d0c3fd..7c732f9 100644
--- a/src/rules/runtime-rules.ts
+++ b/src/rules/runtime-rules.ts
@@ -3,10 +3,27 @@ import { ParsedMcpConfig } from '../parser.js';
 import { Rule } from './index.js';
 
 const SECRET_PATTERNS: RegExp[] = [
-  /sk-[a-zA-Z0-9]{20,}/i,           // OpenAI API key
-  /ghp_[a-zA-Z0-9]{36}/i,            // GitHub PAT
-  /AKIA[0-9A-Z]{16}/i,               // AWS access key
-  /[Pp]assword\s*[=:]\s*\S{8,}/,     // Password assignment
+  // OpenAI / Anthropic keys. Modern keys carry a prefix and may contain
+  // hyphens/underscores in the body: project (sk-proj-), service account
+  // (sk-svcacct-), admin (sk-admin-), and Anthropic (sk-ant-) keys.
+  /sk-(?:proj|svcacct|admin|ant)-[A-Za-z0-9_-]{20,}/i,
+  // Legacy unprefixed OpenAI keys (sk- followed by a long alphanumeric run).
+  /sk-[A-Za-z0-9]{32,}/i,
+  // GitHub tokens: PAT (ghp_), OAuth (gho_), user-to-server (ghu_),
+  // server-to-server (ghs_), and refresh (ghr_) tokens.
+  /gh[pousr]_[A-Za-z0-9]{36,}/,
+  // GitHub fine-grained personal access tokens.
+  /github_pat_[A-Za-z0-9_]{22,}/,
+  // AWS access key ID.
+  /AKIA[0-9A-Z]{16}/,
+  // Google API key.
+  /AIza[0-9A-Za-z_-]{35}/,
+  // Slack tokens (bot/user/app/refresh).
+  /xox[baprs]-[0-9A-Za-z-]{10,}/,
+  // Stripe live secret / restricted keys.
+  /(?:sk|rk)_live_[0-9A-Za-z]{16,}/,
+  // Password assignment.
+  /[Pp]assword\s*[=:]\s*\S{8,}/,
 ];
 
 export const runtimeRules: Rule[] = [