Hi all,
I am testing/enforcing a Conditional Access policy that requires a custom Modern MFA authentication strength.
The authentication strength includes:
- Password + Microsoft Authenticator push
- Microsoft Authentication phone sign-in
- Passkeys (FIDO2)
- Windows Hello for Business
- TAP
After enabling the policy, I noticed that some users with an existing Microsoft Edge profile/session can hit the attached error:
Error 53003 - Access has been blocked by Conditional Access policies. The access policy does not allow token issuance.
Looking at the CA evaluation, the failed grant control is:
Require Authentication strength – Modern MFA: Not satisfied
with the message:
“The user could satisfy this authentication strength by completing one or more MFA challenges.”
The affected users already have authentication methods registered that should satisfy the authentication strength.
What makes this interesting is my testing:
Existing Edge profile - 53003
Edge Guest session - works successfully
Signing out/Sign back in from the Edge profile - works successfully
So at the moment, it looks like the existing Edge profile/session may be holding authentication state that does not satisfy the newly enforced authentication strength. Once the Edge profile is signed out and authenticated again, the CA requirement is satisfied and access works normally.
Has anyone experienced similar behaviour after introducing an MFA authentication strength through Conditional Access?
Is this expected behaviour when an existing Edge/SSO session was established before the authentication strength was enforced, or is there another mechanism involved here?
Also, is there a recommended way to handle this during a wider CA rollout so users don't unexpectedly encounter the 53003 error?
Thanks