Account Takeover
ATO.
An attack where a legitimate user's account is compromised and accessed by an unauthorized party, the dominant CIAM threat in 2026.
Credential stuffing remains the volume leader for ATO; AitM phishing is the most-effective vector against MFA-protected accounts; recovery flow abuse is the most-under-defended back door in production deployments. The full layered defense is documented in the account takeover defense guide.
Scam-driven takeovers, where the victim is talked into handing over access, are covered in the Scam Atlas entries on fake bank support calls, SIM swaps and MFA fatigue.
Common questions
What's the most common ATO vector in 2026?
Do passkeys eliminate ATO?
How do I measure ATO rate?
Related terms
In the guides
Account Takeover Defense: A Layered Approach for 2026
ATO is the single largest CIAM threat in 2026. The defense stack is layered, credential stuffing protection, MFA, session management, and recovery design, each addressing a different attack class.
Passwordless Authentication: A 2026 Practitioner's Guide
How passkeys, magic links, and biometrics replace passwords in CIAM, with implementation patterns, adoption data, and vendor support.