diff --git a/.changeset/moody-sites-lead.md b/.changeset/moody-sites-lead.md
new file mode 100644
index 00000000000..92c03b82f50
--- /dev/null
+++ b/.changeset/moody-sites-lead.md
@@ -0,0 +1,5 @@
+---
+'@clerk/shared': major
+---
+
+Adjust features parsing to throw errors on unknown scopes.
diff --git a/packages/clerk-js/bundlewatch.config.json b/packages/clerk-js/bundlewatch.config.json
index 3bd20ec6fee..272648511b7 100644
--- a/packages/clerk-js/bundlewatch.config.json
+++ b/packages/clerk-js/bundlewatch.config.json
@@ -4,7 +4,7 @@
     { "path": "./dist/clerk.browser.js", "maxSize": "66KB" },
     { "path": "./dist/clerk.chips.browser.js", "maxSize": "66KB" },
     { "path": "./dist/clerk.legacy.browser.js", "maxSize": "106KB" },
-    { "path": "./dist/clerk.no-rhc.js", "maxSize": "305KB" },
+    { "path": "./dist/clerk.no-rhc.js", "maxSize": "307KB" },
     { "path": "./dist/clerk.native.js", "maxSize": "65KB" },
     { "path": "./dist/vendors*.js", "maxSize": "7KB" },
     { "path": "./dist/coinbase*.js", "maxSize": "36KB" },
diff --git a/packages/shared/src/__tests__/authorization.spec.ts b/packages/shared/src/__tests__/authorization.spec.ts
new file mode 100644
index 00000000000..7037305ed43
--- /dev/null
+++ b/packages/shared/src/__tests__/authorization.spec.ts
@@ -0,0 +1,44 @@
+import { describe, expect, it } from 'vitest';
+
+import { createCheckAuthorization, splitByScope } from '../authorization';
+
+describe('createCheckAuthorization', () => {
+  it('correctly parses features', () => {
+    const checkAuthorization = createCheckAuthorization({
+      userId: 'user_123',
+      orgId: 'org_123',
+      orgRole: 'admin',
+      orgPermissions: ['org:read'],
+      features: 'o:reservations,u:dashboard',
+      plans: 'free_user,plus_user',
+      factorVerificationAge: [1000, 2000],
+    });
+    expect(checkAuthorization({ feature: 'o:reservations' })).toBe(true);
+    expect(checkAuthorization({ feature: 'org:reservations' })).toBe(true);
+    expect(checkAuthorization({ feature: 'organization:reservations' })).toBe(true);
+    expect(checkAuthorization({ feature: 'reservations' })).toBe(true);
+    expect(checkAuthorization({ feature: 'u:dashboard' })).toBe(true);
+    expect(checkAuthorization({ feature: 'user:dashboard' })).toBe(true);
+    expect(checkAuthorization({ feature: 'dashboard' })).toBe(true);
+
+    expect(() => checkAuthorization({ feature: 'lol:dashboard' })).toThrow('Invalid scope: lol');
+  });
+});
+
+describe('splitByScope', () => {
+  it('correctly splits features by scope', () => {
+    const { org, user } = splitByScope('o:reservations,u:dashboard');
+    expect(org).toEqual(['reservations']);
+    expect(user).toEqual(['dashboard']);
+  });
+
+  it('correctly splits features by scope with multiple scopes', () => {
+    const { org, user } = splitByScope('o:reservations,u:dashboard,ou:support-chat,uo:billing');
+    expect(org).toEqual(['reservations', 'support-chat', 'billing']);
+    expect(user).toEqual(['dashboard', 'support-chat', 'billing']);
+  });
+
+  it('throws an error if the claim element is missing a colon', () => {
+    expect(() => splitByScope('reservations,dashboard')).toThrow('Invalid claim element (missing colon): reservations');
+  });
+});
diff --git a/packages/shared/src/authorization.ts b/packages/shared/src/authorization.ts
index 0834ecb86e2..db2af474f93 100644
--- a/packages/shared/src/authorization.ts
+++ b/packages/shared/src/authorization.ts
@@ -65,6 +65,9 @@ const ALLOWED_LEVELS = new Set<SessionVerificationLevel>(['first_factor', 'secon
 
 const ALLOWED_TYPES = new Set<SessionVerificationTypes>(['strict_mfa', 'strict', 'moderate', 'lax']);
 
+const ORG_SCOPES = new Set(['o', 'org', 'organization']);
+const USER_SCOPES = new Set(['u', 'user']);
+
 // Helper functions
 const isValidMaxAge = (maxAge: any) => typeof maxAge === 'number' && maxAge > 0;
 const isValidLevel = (level: any) => ALLOWED_LEVELS.has(level);
@@ -100,17 +103,26 @@ const checkOrgAuthorization: CheckOrgAuthorization = (params, options) => {
 
 const checkForFeatureOrPlan = (claim: string, featureOrPlan: string) => {
   const { org: orgFeatures, user: userFeatures } = splitByScope(claim);
-  const [scope, _id] = featureOrPlan.split(':');
-  const id = _id || scope;
-
-  if (scope === 'org') {
-    return orgFeatures.includes(id);
-  } else if (scope === 'user') {
-    return userFeatures.includes(id);
-  } else {
-    // Since org scoped features will not exist if there is not an active org, merging is safe.
-    return [...orgFeatures, ...userFeatures].includes(id);
+  const [rawScope, rawId] = featureOrPlan.split(':');
+  const hasExplicitScope = rawId !== undefined;
+  const scope = rawScope;
+  const id = rawId || rawScope;
+
+  if (hasExplicitScope && !ORG_SCOPES.has(scope) && !USER_SCOPES.has(scope)) {
+    throw new Error(`Invalid scope: ${scope}`);
   }
+
+  if (hasExplicitScope) {
+    if (ORG_SCOPES.has(scope)) {
+      return orgFeatures.includes(id);
+    }
+    if (USER_SCOPES.has(scope)) {
+      return userFeatures.includes(id);
+    }
+  }
+
+  // Since org scoped features will not exist if there is not an active org, merging is safe.
+  return [...orgFeatures, ...userFeatures].includes(id);
 };
 
 const checkBillingAuthorization: CheckBillingAuthorization = (params, options) => {
@@ -127,13 +139,34 @@ const checkBillingAuthorization: CheckBillingAuthorization = (params, options) =
 };
 
 const splitByScope = (fea: string | null | undefined) => {
-  const features = fea ? fea.split(',').map(f => f.trim()) : [];
+  const org: string[] = [];
+  const user: string[] = [];
 
-  // TODO: make this more efficient
-  return {
-    org: features.filter(f => f.split(':')[0].includes('o')).map(f => f.split(':')[1]),
-    user: features.filter(f => f.split(':')[0].includes('u')).map(f => f.split(':')[1]),
-  };
+  if (!fea) {
+    return { org, user };
+  }
+
+  const parts = fea.split(',');
+  for (let i = 0; i < parts.length; i++) {
+    const part = parts[i].trim();
+    const colonIndex = part.indexOf(':');
+    if (colonIndex === -1) {
+      throw new Error(`Invalid claim element (missing colon): ${part}`);
+    }
+    const scope = part.slice(0, colonIndex);
+    const value = part.slice(colonIndex + 1);
+
+    if (scope === 'o') {
+      org.push(value);
+    } else if (scope === 'u') {
+      user.push(value);
+    } else if (scope === 'ou' || scope === 'uo') {
+      org.push(value);
+      user.push(value);
+    }
+  }
+
+  return { org, user };
 };
 
 const validateReverificationConfig = (config: ReverificationConfig | undefined | null) => {