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bug(fix): Support webauthn implementations that return plain object #20401

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Merged
vpomerleau merged 1 commit into from
Apr 24, 2026
Merged

bug(fix): Support webauthn implementations that return plain object #20401

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56 changes: 52 additions & 4 deletions packages/fxa-settings/src/lib/passkeys/webauthn.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -110,8 +110,6 @@ describe('isWebAuthnLevel3Supported', () => {
});
});

// ─── createCredential ─────────────────────────────────────────────────────────

describe('createCredential', () => {
let mockPKC: Record<string, jest.Mock>;
let mockCreate: jest.Mock;
Expand Down Expand Up @@ -183,9 +181,34 @@ describe('createCredential', () => {
expect(spy).toHaveBeenCalled();
spy.mockRestore();
});
});

// ─── getCredential ────────────────────────────────────────────────────────────
it('resolves via duck-typed toJSON() when credential is a plain object (e.g. 1Password)', async () => {
// 1Password returns a plain object that mimics PublicKeyCredential
// but is not an actual instance of the class.
const proxyCredential = {
id: mockCredentialJSON.id,
rawId: new ArrayBuffer(8),
type: 'public-key',
authenticatorAttachment: 'platform',
response: {},
getClientExtensionResults: jest.fn().mockReturnValue({}),
toJSON: jest.fn().mockReturnValue(mockCredentialJSON),
};
mockCreate.mockResolvedValue(proxyCredential);

const result = await createCredential(mockCreationOptions);
expect(result).toEqual(mockCredentialJSON);
expect(proxyCredential.toJSON).toHaveBeenCalled();
});

it('throws when credential lacks toJSON()', async () => {
mockCreate.mockResolvedValue({ id: 'no-toJSON', type: 'public-key' });
await expect(createCredential(mockCreationOptions)).rejects.toMatchObject({
name: 'UnknownError',
message: expect.stringContaining('without toJSON()'),
});
});
});

describe('getCredential', () => {
let mockPKC: Record<string, jest.Mock>;
Expand Down Expand Up @@ -258,4 +281,29 @@ describe('getCredential', () => {
expect(spy).toHaveBeenCalled();
spy.mockRestore();
});

it('resolves via duck-typed toJSON() when credential is a plain object (e.g. 1Password)', async () => {
const proxyCredential = {
id: mockCredentialJSON.id,
rawId: new ArrayBuffer(8),
type: 'public-key',
authenticatorAttachment: 'platform',
response: {},
getClientExtensionResults: jest.fn().mockReturnValue({}),
toJSON: jest.fn().mockReturnValue(mockCredentialJSON),
};
mockGet.mockResolvedValue(proxyCredential);

const result = await getCredential(mockRequestOptions);
expect(result).toEqual(mockCredentialJSON);
expect(proxyCredential.toJSON).toHaveBeenCalled();
});

it('throws when credential lacks toJSON()', async () => {
mockGet.mockResolvedValue({ id: 'no-toJSON', type: 'public-key' });
await expect(getCredential(mockRequestOptions)).rejects.toMatchObject({
name: 'UnknownError',
message: expect.stringContaining('without toJSON()'),
});
});
});
85 changes: 43 additions & 42 deletions packages/fxa-settings/src/lib/passkeys/webauthn.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -174,6 +174,47 @@ export function isWebAuthnLevel3Supported(): boolean {
);
}

// ─── Credential extraction ──────────────────────────────────────────────────

/** Type guard for objects that can serialize to credential JSON. */
function hasToJSON(
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@dschom dschom Apr 24, 2026

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👍

value: unknown
): value is { toJSON: () => PublicKeyCredentialJSON } {
return (
typeof value === 'object' &&
value !== null &&
'toJSON' in value &&
typeof value.toJSON === 'function'
);
}

/**
* Extracts `PublicKeyCredentialJSON` from a browser credential result.
*
* Prefers duck-typing (`toJSON()`) over `instanceof PublicKeyCredential`
* because password managers (e.g. 1Password) may return a plain object
* that has all the right fields but is not a real `PublicKeyCredential`.
*
* No client-side shape validation of the `toJSON()` return value —
* `@simplewebauthn/server:verifyRegistrationResponse` performs strict
* WebAuthn spec validation server-side and rejects malformed data.
*/
function toCredentialJSON(
rawCredential: Credential | null,
operation: string
): PublicKeyCredentialJSON {
if (!rawCredential) {
throw new DOMException(`${operation} returned null`, 'UnknownError');
}
if (hasToJSON(rawCredential)) {
return rawCredential.toJSON();
}
throw new DOMException(
`${operation} returned a credential without toJSON()`,
'UnknownError'
);
}

// ─── Wrapper functions ────────────────────────────────────────────────────────

const DEFAULT_TIMEOUT_MS = 60_000;
Expand Down Expand Up @@ -217,27 +258,7 @@ export async function createCredential(
signal: controller.signal,
});

if (!rawCredential) {
throw new DOMException(
'navigator.credentials.create returned null',
'UnknownError'
);
}
if (rawCredential instanceof PublicKeyCredential) {
return rawCredential.toJSON();
}
const actualType =
(rawCredential as Credential).constructor?.name ?? typeof rawCredential;
const keyInfo = Object.entries(rawCredential as object)
.map(
([k, v]) =>
`${k}: ${v instanceof ArrayBuffer ? 'ArrayBuffer' : typeof v}`
)
.join(', ');
throw new DOMException(
`navigator.credentials.create returned unexpected credential type: ${actualType} — fields: {${keyInfo}}`,
'UnknownError'
);
return toCredentialJSON(rawCredential, 'navigator.credentials.create');
} catch (e) {
if (timedOut) {
throw new DOMException('WebAuthn operation timed out', 'TimeoutError');
Expand Down Expand Up @@ -287,27 +308,7 @@ export async function getCredential(
signal: controller.signal,
});

if (!rawCredential) {
throw new DOMException(
'navigator.credentials.get returned null',
'UnknownError'
);
}
if (rawCredential instanceof PublicKeyCredential) {
return rawCredential.toJSON();
}
const actualType =
(rawCredential as Credential).constructor?.name ?? typeof rawCredential;
const keyInfo = Object.entries(rawCredential as object)
.map(
([k, v]) =>
`${k}: ${v instanceof ArrayBuffer ? 'ArrayBuffer' : typeof v}`
)
.join(', ');
throw new DOMException(
`navigator.credentials.get returned unexpected credential type: ${actualType} — fields: {${keyInfo}}`,
'UnknownError'
);
return toCredentialJSON(rawCredential, 'navigator.credentials.get');
} catch (e) {
if (timedOut) {
throw new DOMException('WebAuthn operation timed out', 'TimeoutError');
Expand Down
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