Passkeys protect against password theft and phishing, but they do not by themselves prove that a real human is present at the moment of authentication. Where fraudsters use device compromise, deepfakes, or social engineering, the missing control is live identity assurance. Pairing passkeys with biometric verification closes that gap by confirming both credential possession and user presence.
Why passkeys reduce phishing but not all takeover paths
Passkeys materially improve authentication because they remove reusable passwords and make classic phishing much harder. The remaining gap is that a passkey confirms possession of a bound credential, not necessarily that the authenticating person is the intended, live user in a high-assurance transaction. If the endpoint, session, or recovery path is compromised, an attacker can still ride through a legitimate authentication event.
That is why high-assurance journeys care about more than login strength alone. A passkey can tell you “this device and this credential are valid,” but it does not fully answer “is the right human present, right now, for this specific step?” In practice, account takeover risk often shifts from password theft to device compromise, session abuse, help-desk manipulation, or social engineering around recovery and step-up verification.
Strong identity guidance has long treated phishing-resistant authentication as necessary but not sufficient. NIST SP 800-63 Digital Identity Guidelines is useful here because it separates authenticator strength from overall assurance, which is exactly the distinction that matters in high-value journeys. For a broader control view, NIST Cybersecurity Framework 2.0 reinforces that identity controls must be paired with governance, detection, and response, not treated as a single protective layer.
Where takeover risk still appears in practice
The most common failure mode is not a cracked passkey, but a trusted environment being abused around it. If malware or remote-access tooling controls the browser or device, the attacker can authenticate as the user after the passkey challenge is satisfied. If an organisation relies on weak recovery, shared help-desk knowledge, or a one-time step-up flow with no live presence check, the attacker can redirect the journey without ever defeating the passkey itself.
This is also why fraud and identity teams often care about transaction context, not just authentication ceremony. In a high-assurance journey, the security question is whether the session is bound to the right person, on the right device, for the right action, under the right level of scrutiny. A passkey is excellent at reducing credential replay and phishing, but it does not by itself close the gap created by endpoint compromise, stolen sessions, or non-live impersonation.
Practitioner evidence from real-world compromise patterns supports that view. Ultimate Guide to NHIs shows how often security failures come from over-trusted identity material, while GitHub Personal Account Breach and SonicWall VPN Mass Breach via Stolen Credentials are reminders that takeover frequently succeeds through surrounding control failures rather than through the primary authenticator alone.
What closes the gap in high-assurance journeys
The missing control is live identity assurance, usually implemented as a stronger step-up at the moment the risk matters. Biometric verification is one common option because it can confirm that a real, present person is participating when the action is sensitive. The practical goal is not to replace passkeys, but to pair them with a control that verifies presence, reduces remote misuse, and raises the cost of social engineering or device capture.
What to verify: Treat passkey success as an authentication event, not a full trust decision. For account recovery, payment release, privilege escalation, or high-risk profile changes, verify that the second factor or step-up control checks live presence and is resistant to replay, remote assistance abuse, and scripted abuse.
Common mistake: Organisations often assume that phishing-resistant login removes the need for step-up assurance in sensitive flows. It does not, because the takeover path may start after login, inside the session, or through the recovery process rather than through password theft.
Practitioner takeaway: Use passkeys to eliminate password and phishing risk, but require a separate live-assurance signal wherever the decision has fraud, recovery, or account-change impact; that is the point where possession of a credential stops being enough.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-63, NIST CSF 2.0 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-63 | Authenticator Assurance and Phishing-Resistance — Authenticator Assurance and Phishing-Resistance | Passkeys need assurance framing beyond simple login strength. |
| Recommendation — Use phishing-resistant authenticators, then add step-up assurance for high-risk actions. | ||
| NIST CSF 2.0 | PR.AA — Identity Management, Authentication and Access Control | The question is about authentication strength versus residual takeover risk. |
| Recommendation — Pair strong authentication with access governance and monitoring for sensitive journeys. | ||
| CIS Controls v8 | 6 — Access Control Management | High-assurance journeys need stronger control over sensitive access decisions. |
| Recommendation — Restrict and verify sensitive access paths before allowing high-impact account actions. | ||
Related resources from NHI Mgmt Group
- Why do passkeys still leave account takeover risk in place?
- Why do organisations replace SMS OTP in high-risk journeys before full account-wide migration?
- Why do passkeys reduce account takeover risk more effectively than OTP?
- Why do weak session controls and missing MFA create such high account takeover risk?
