diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index e71a47d0b..3d17e23fd 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -1498,29 +1498,31 @@ X509 Certificate ASN1 (TBSCertificate, invalid SubjectPublicKeyinfo, check faile
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
 x509parse_crt:"308196308180a0030201008204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210fffffffffffffffffffffffffffffffe0202ffff300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_PK_INVALID_PUBKEY
 
-X509 Certificate ASN1 (TBSCertificate v3, Optional UIDs, Extensions not present)
+# We don't expect MBEDTLS_ERR_ASN1_UNEXPECTED_TAG here because the IssuerID is optional;
+# the stack is expected to ignore it and will hence end up with a length mismatch.
+X509 Certificate ASN1 (TBSCertificate, invalid IssuerID, invalid tag)
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
-x509parse_crt:"308183308180a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092a864886f70d010101050003190030160210ffffffffffffffffffffffffffffffff0202ffff":"":MBEDTLS_ERR_X509_INVALID_ALG + MBEDTLS_ERR_ASN1_OUT_OF_DATA
+x509parse_crt:"308197308181a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092a864886f70d010101050003190030160210ffffffffffffffffffffffffffffffff0202ffff05300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG
 
-X509 Certificate ASN1 (TBSCertificate v3, issuerID wrong tag)
+X509 Certificate ASN1 (TBSCertificate, invalid IssuerID, length missing)
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
-x509parse_crt:"308184308181a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092a864886f70d010101050003190030160210ffffffffffffffffffffffffffffffff0202ffff00":"":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG
+x509parse_crt:"308197308181a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa1300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_OUT_OF_DATA
 
-X509 Certificate ASN1 (TBSCertificate v3, UIDs, no ext)
+X509 Certificate ASN1 (TBSCertificate, invalid IssuerID, invalid length encoding)
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
-x509parse_crt:"308189308186a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092a864886f70d010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa101aaa201bb":"":MBEDTLS_ERR_X509_INVALID_ALG + MBEDTLS_ERR_ASN1_OUT_OF_DATA
+x509parse_crt:"308198308182a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa185300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_INVALID_LENGTH
 
-X509 Certificate ASN1 (TBSCertificate v3, UIDs, invalid length)
+X509 Certificate ASN1 (TBSCertificate, invalid IssuerID, length out of bounds)
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
-x509parse_crt:"308189308186a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092a864886f70d010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa185aaa201bb":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_INVALID_LENGTH
+x509parse_crt:"308198308182a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa101300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_OUT_OF_DATA
 
-X509 Certificate ASN1 (TBSCertificate v3, ext empty)
+X509 Certificate ASN1 (TBSCertificate, no IssuerID, invalid SubjectID, length missing)
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
-x509parse_crt:"30818b308188a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092a864886f70d010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa101aaa201bba300":"":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_OUT_OF_DATA
+x509parse_crt:"308197308181a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa2300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_OUT_OF_DATA
 
-X509 Certificate ASN1 (TBSCertificate v3, ext length mismatch)
+X509 Certificate ASN1 (TBSCertificate, no IssuerID, invalid SubjectID, invalid length encoding)
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
-x509parse_crt:"30818e30818ba0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092a864886f70d010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa101aaa201bba303300000":"":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_LENGTH_MISMATCH
+x509parse_crt:"308198308182a0030201028204deadbeef300d06092a864886f70d01010b0500300c310a30080600130454657374301c170c303930313031303030303030170c303931323331323335393539300c310a30080600130454657374302a300d06092A864886F70D010101050003190030160210ffffffffffffffffffffffffffffffff0202ffffa285300d06092a864886f70d01010b0500030200ff":"":MBEDTLS_ERR_X509_INVALID_FORMAT + MBEDTLS_ERR_ASN1_INVALID_LENGTH
 
 X509 Certificate ASN1 (TBSCertificate v3, first ext invalid)
 depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA256_C