From c7bd1be3e470a94277356b0156b07285a9d984e4 Mon Sep 17 00:00:00 2001
From: Hampus <hampus@fluxer.app>
Date: Wed, 30 Sep 2026 23:01:37 +0200
Subject: [PATCH] fix(auth): offer every transport for passkeys stored without
 any (#3077)

---
 fluxer_api/src/api/auth/AuthMfa.ts            | 11 +++--
 .../api/auth/tests/WebAuthnMfaLogin.test.ts   | 43 +++++++++++++++++++
 .../src/api/auth/tests/WebAuthnTestUtils.ts   |  6 ++-
 3 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/fluxer_api/src/api/auth/AuthMfa.ts b/fluxer_api/src/api/auth/AuthMfa.ts
index ab8b7aec5..2128103c3 100644
--- a/fluxer_api/src/api/auth/AuthMfa.ts
+++ b/fluxer_api/src/api/auth/AuthMfa.ts
@@ -168,12 +168,17 @@ export async function verifyMfaCode(ctx: ApiContext, params: VerifyMfaCodeParams
 	return false;
 }
 
+type CredentialTransport = 'usb' | 'nfc' | 'ble' | 'internal' | 'cable' | 'hybrid';
+
+const ALL_CREDENTIAL_TRANSPORTS: Array<CredentialTransport> = ['internal', 'hybrid', 'usb', 'nfc', 'ble'];
+
 function toCredentialDescriptor(credential: WebAuthnCredential) {
 	return {
 		id: credential.credentialId,
-		transports: credential.transports
-			? (Array.from(credential.transports) as Array<'usb' | 'nfc' | 'ble' | 'internal' | 'cable' | 'hybrid'>)
-			: undefined,
+		transports:
+			credential.transports && credential.transports.size > 0
+				? (Array.from(credential.transports) as Array<CredentialTransport>)
+				: ALL_CREDENTIAL_TRANSPORTS,
 	};
 }
 
diff --git a/fluxer_api/src/api/auth/tests/WebAuthnMfaLogin.test.ts b/fluxer_api/src/api/auth/tests/WebAuthnMfaLogin.test.ts
index e95668e2e..be6e95ba5 100644
--- a/fluxer_api/src/api/auth/tests/WebAuthnMfaLogin.test.ts
+++ b/fluxer_api/src/api/auth/tests/WebAuthnMfaLogin.test.ts
@@ -65,6 +65,7 @@ describe('WebAuthn MFA login', () => {
 		expect(mfaOptions.userVerification).toBe('discouraged');
 		expect(mfaOptions.allowCredentials).toBeTruthy();
 		expect(mfaOptions.allowCredentials!.length).toBeGreaterThan(0);
+		expect(mfaOptions.allowCredentials![0]!.transports).toEqual(['internal']);
 		if (mfaOptions.rpId) {
 			device.rpId = mfaOptions.rpId;
 		}
@@ -87,6 +88,48 @@ describe('WebAuthn MFA login', () => {
 			.execute();
 		expect(userInfo.id).toBe(account.userId);
 	});
+	it('offers every transport for a passkey registered without transports', async () => {
+		const account = await createTestAccount(harness);
+		const device = createWebAuthnDevice();
+		device.transports = null;
+		const secret = createTotpSecret();
+		await createBuilder(harness, account.token)
+			.post('/users/@me/mfa/totp/enable')
+			.body({secret, code: generateTotpCode(secret), password: account.password})
+			.execute();
+		await registerWebAuthnCredential(harness, account.token, device, () => ({
+			mfa_method: 'totp',
+			mfa_code: generateTotpCode(secret),
+		}));
+		await setWebAuthnTwoFactor(harness, account.token, true, {
+			mfa_method: 'totp',
+			mfa_code: generateTotpCode(secret),
+		});
+		const loginResp = (await loginUser(harness, {
+			email: account.email,
+			password: account.password,
+		})) as LoginMfaResponse;
+		const mfaOptions = await createBuilderWithoutAuth<WebAuthnAuthenticationOptions>(harness)
+			.post('/auth/login/mfa/webauthn/authentication-options')
+			.body({ticket: loginResp.ticket})
+			.execute();
+		expect(mfaOptions.allowCredentials).toEqual([
+			{
+				id: device.credentialId.toString('base64url'),
+				type: 'public-key',
+				transports: ['internal', 'hybrid', 'usb', 'nfc', 'ble'],
+			},
+		]);
+		const webauthnMfaLogin = await createBuilderWithoutAuth<{token: string}>(harness)
+			.post('/auth/login/mfa/webauthn')
+			.body({
+				response: createAuthenticationResponse(device, mfaOptions),
+				challenge: mfaOptions.challenge,
+				ticket: loginResp.ticket,
+			})
+			.execute();
+		expect(webauthnMfaLogin.token).toBeTruthy();
+	});
 	it('issues a session token instead of an MFA ticket when passkey two-factor is left off', async () => {
 		const account = await createTestAccount(harness);
 		const device = createWebAuthnDevice();
diff --git a/fluxer_api/src/api/auth/tests/WebAuthnTestUtils.ts b/fluxer_api/src/api/auth/tests/WebAuthnTestUtils.ts
index 5588a44d9..f61ec0e7e 100644
--- a/fluxer_api/src/api/auth/tests/WebAuthnTestUtils.ts
+++ b/fluxer_api/src/api/auth/tests/WebAuthnTestUtils.ts
@@ -21,6 +21,7 @@ export interface WebAuthnDevice {
 	rpId: string;
 	origin: string;
 	signCount: number;
+	transports?: Array<string> | null;
 }
 
 export interface WebAuthnRegistrationOptions {
@@ -47,6 +48,7 @@ export interface WebAuthnAuthenticationOptions {
 	allowCredentials?: Array<{
 		id: string;
 		type: string;
+		transports?: Array<string>;
 	}>;
 	userVerification: string;
 }
@@ -75,7 +77,7 @@ export interface WebAuthnTwoFactorResult {
 interface AuthenticatorAttestationResponse {
 	clientDataJSON: string;
 	attestationObject: string;
-	transports: Array<string>;
+	transports?: Array<string>;
 }
 
 interface AuthenticatorAssertionResponse {
@@ -363,7 +365,7 @@ export function createRegistrationResponse(
 		response: {
 			clientDataJSON: encodeBase64URL(clientDataJSON),
 			attestationObject: encodeBase64URL(attestationObject),
-			transports: ['internal'],
+			...(device.transports === null ? {} : {transports: device.transports ?? ['internal']}),
 		},
 	};
 }