ISC Identity And Access Management Architecture Practice Question
In a SAML 2.0 federation architecture, the Service Provider (SP) returns a 403 error during the assertion consumption phase. After verifying the digital signature, what is the most likely cause?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Subject NameID mismatch
If the signature is valid but access is denied, the NameID or attributes in the assertion often do not match the expected user mapping or authorization requirements at the SP.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Encryption algorithm mismatch
Why it's wrong here
This would lead to a failure to decrypt the assertion, preventing the process from reaching the 403 stage.
- ✗
Expired metadata
Why it's wrong here
Metadata expiration usually causes a handshake failure, not a 403 after assertion processing.
- ✗
Assertion Consumer Service (ACS) URL mismatch
Why it's wrong here
This typically results in a 400 Bad Request or a failure to post the assertion.
- ✓
Subject NameID mismatch
Why this is correct
A mismatch in the unique identifier mapping often results in the SP rejecting the session due to unknown identity.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official (ISC)² exam blueprint
This ISC practice question is part of Courseiva's free (ISC)² certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ISC exam.