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Fencer Intel
medium —

GHSA-8f6j-263m-g72x json

Apple App Store Server Python Library: SignedDataVerifier accepts stale OCSP GOOD responses and can bypass certificate revocation checks

published 3mo ago modified 3mo ago

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
—
no score, EPSS covers CVEs only
public exploits
0
none known

Summary

### Summary `SignedDataVerifier` attempts to perform online revocation checking when `enable_online_checks=True`, but its OCSP validation logic accepts stale `GOOD` responses as valid indefinitely. In `appstoreserverlibrary/signed_data_verifier.py`, `_ChainVerifier.check_ocsp_status()` verifies the OCSP response signature and CertID match, but never validates the freshness window carried by `producedAt`, `thisUpdate`, or `nextUpdate`.

As a result, a previously valid signed OCSP `GOOD` response can be replayed after it is expired, and the library will still treat the certificate as good. If an App Store signing certificate or intermediate is ever revoked, applications using this library with online checks enabled can continue accepting JWS objects signed with the revoked key as long as a stale signed OCSP response is replayed.

Patch / fix

  • pypi app-store-server-library 3.1.2

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Affected packages

ecosystem package affected fixed in
pypi app-store-server-library
>=0.2.0, <3.1.2
3.1.2

Classification

Weakness
  • CWE-295 Improper Certificate Validation
  • CWE-299 Improper Check for Certificate Revocation

References

Sources

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