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Scope OIDC issuer fallback eligibility - #978
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Nilesh Choudhary (4gust) wants to merge 3 commits into
Open
Nilesh Choudhary (4gust) wants to merge 3 commits into
Nilesh Choudhary (4gust) wants to merge 3 commits into
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Restrict regional issuer patterns to built-in Microsoft authorities and prevent their CIAM/B2C fallback. Preserve native parsing behavior, reject before endpoint use, and evict rejected discovery metadata for recovery. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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🟡 Changes recommended
Issuer-validation exceptions bypass cache eviction, leaving malformed HTTP 200 metadata cached for 24 hours and preventing recovery with the same cache even after metadata is corrected.
1 open issue
What changed in this PR
This PR tightens issuer fallback eligibility for explicit oidc_authority in MSAL Python while preserving ordinary authority behavior and existing URL parsing.
Changes:
- Limits regional issuer fallback to built-in Microsoft authorities and disables their B2C/CIAM fallback.
- Moves issuer validation before endpoint consumption and adds cache eviction for rejected issuers.
- Adds policy, boundary, and recovery tests, plus documentation of the behavior change.
| File | Description |
|---|---|
| tests/test_authority.py | Adds issuer-policy, parsing-boundary, and cache-recovery coverage. |
| RELEASES.md | Documents compatibility changes and their scope. |
| msal/throttled_http_client.py | Extracts GET cache-key generation and adds targeted eviction. |
| msal/authority.py | Restricts fallback eligibility and validates issuers before using endpoints. |
| msal/application.py | Documents explicit OIDC issuer validation and cache behavior. |
Review effort: Balanced
Evict rejected discovery metadata when issuer parsing raises, without changing the original exception. Cover repeated malformed-issuer rejection, valid recovery, and accepted metadata caching. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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🟡 Changes recommended
_ExpiringMapping.pop() leaves orphaned expiry-heap records, allowing repeated rejected constructions with a shared HTTP cache to grow the in-memory or serialized cache beyond the 1,024-entry limit.
1 open issue
1 resolved since last review
Review effort: Balanced
Invalidate rejected responses and rebuild the expiry heap from live entries under the existing cache lock. Preserve accepted responses, expiry ordering, and capacity eviction without accumulating orphans. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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Summary
Validation
python -m pytest tests\test_authority.py tests\test_application.py tests\test_throttled_http_client.py tests\test_individual_cache.py -q --tb=short231 passed, 1 pre-existing skip; 308 subtests passed (Windows, Python 3.12.10).