YubiKey 5 review 2026: features, EUCLEAK and prices

The YubiKey 5 series is the safe, capable default for hardware security keys: one device that handles passkeys, FIDO2 and U2F, one-time passwords, smart-card login and OpenPGP, and it is built in Sweden. It costs more than FIDO-only alternatives and its firmware cannot be updated, so check the firmware version when you buy. This review is an editorial assessment based on Yubico documentation, published advisories, specifications and prices as of October 2026. We did not run laboratory tests.

Quick verdict

Criterion	Assessment
FIDO2 and U2F	Yes, including FIDO2 CTAP 2.1; 100 passkey slots (per Yubico)
Other functions	Yubico OTP, OATH TOTP and HOTP, PIV smart card, OpenPGP, static passwords
Connectors	USB-A, USB-C, NFC, Lightning (5Ci only)
Firmware	5.8 on current stock; cannot be updated on the device
Open source	Firmware closed; much of the host-side software is open
Origin	Sweden / USA; keys made in Sweden
Known issue	EUCLEAK affects firmware before 5.7
Price	Roughly 59 to 90 EUR depending on model and country

Security

A security key keeps a private key in hardware and signs a login challenge only when you touch it, which makes phishing very hard, because the key checks the website address. That is the core idea of phishing-resistant MFA. The YubiKey 5 supports FIDO2 and U2F, so it works with passkeys and with older two-factor flows. Our guide to hardware security keys explains how it differs from SMS codes and authenticator apps.

The best-known weakness is EUCLEAK, published in September 2024 by researchers who found a side-channel flaw in the ECDSA implementation of an Infineon cryptographic library. Yubico said that YubiKey 5 series and Security Key devices with firmware before 5.7.0 were affected, and it rated the severity moderate with a CVSS score of 4.9. The attack needs physical possession of the key, expensive equipment, custom software and knowledge of the accounts to target, and it could affect FIDO as well as PIV and OpenPGP keys that use ECC. Yubico released firmware 5.7 in May 2024, which uses its own cryptographic library, and published the advisory in September. Because firmware on a YubiKey cannot be updated, older keys remain affected for good. See Yubico’s advisory. For most people, the risk is low. If you are a journalist, activist or administrator facing targeted attacks, replace pre-5.7 keys.

Features

• FIDO2 and passkeys. Device-bound passkeys on the key, with 100 slots according to Yubico. You can also use the key as a second factor for sites without passkey support. Learn how in set up passkeys. The standard behind it is covered under FIDO2 and WebAuthn.
• OATH TOTP and HOTP. Store time-based codes on the key and read them with the Yubico Authenticator app.
• PIV. Smart-card functions for workstation login and certificates.
• OpenPGP. Keep email-signing or SSH keys on the key.
• Yubico OTP and static passwords. Legacy features for specific services.
• Durability. IP68 rating, no battery and no moving parts.

Most home users only touch the FIDO2 function. The rest earns its price if you work in IT, sign email, or manage servers.

Models and pricing (as of October 2026)

Model	Connectors	Approx. price (EUR, incl. VAT)
YubiKey 5 NFC	USB-A, NFC	about 59
YubiKey 5C NFC	USB-C, NFC	about 65 to 69
YubiKey 5C	USB-C	about 65
YubiKey 5 Nano	USB-A, stays in port	about 71
YubiKey 5C Nano	USB-C, stays in port	about 77
YubiKey 5Ci	USB-C, Lightning	about 89

These figures come from Yubico store pages in several European countries and differ slightly between countries. Check the price for your market. Buy at least two keys, because losing your only key can lock you out of accounts.

Privacy and origin

Yubico was founded in Sweden and also has a presence in the United States. Production of the series takes place in Sweden, according to Yubico. The key does not need an account with Yubico to work, and it does not store your identity on a server. It is a local device. Your privacy exposure is mostly the services where you register it, so pair it with a sensible recovery plan, as described in our guide to account recovery.

Who should buy it

Buy a YubiKey 5 if you want one key that covers passkeys, two-factor login, stored one-time codes and, optionally, smart-card and OpenPGP use. It is a strong fit for IT staff, developers, administrators and anyone protecting email or cloud accounts with sensitive data. It is overkill if you only need passkeys for a few accounts, in which case a FIDO-only key costs about half. It is also not the best fit if open source firmware is a hard requirement, because Yubico’s firmware is closed.

Getting started safely

1. Check the firmware version in Yubico’s management software and avoid keys older than 5.7.
2. Register the key with your most important accounts first: email, password manager, cloud storage and your domain registrar.
3. Set a FIDO2 PIN when prompted. The PIN protects passkeys stored on the key if someone finds it.
4. Register a second key at the same time and keep it somewhere safe.
5. Keep printed backup codes for accounts that offer them, and test the recovery path once.

What we could not verify

We relied on Yubico’s product pages, the published EUCLEAK advisory and news coverage, and we did not test any keys ourselves. Euro prices differ by country and between retailers. We could not confirm the exact slot limits on every older firmware generation, and we did not assess the separate YubiKey Bio and FIPS series.

Alternatives

• Best hardware security keys: all five lines side by side.
• YubiKey vs Nitrokey: the closed Swedish key against the open source German one.
• Yubico’s Security Key Series: about 35 EUR, FIDO2 only, 100 passkeys.
• Token2 PIN+: about 25 EUR, up to 300 passkeys, FIDO2 focus.

Conclusion

The YubiKey 5 series is the most complete security key you can buy and a good choice for people who will use more than passkeys. Buy it with firmware 5.7 or newer, pick the connector that matches your devices, and register two keys. If you only want passkeys and two-factor login, or want open source firmware, compare the alternatives in our best hardware security keys list before you spend 60 euros or more per key.