diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index 6f61a7e..9395202 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -217,6 +217,16 @@
 * ``san_rsa_sha1.pem`` and ``san_rsa_sha1.der`` - Contain a certificate
   request using RSA and SHA1 with a subject alternative name extension
   generated using OpenSSL.
+* ``two_basic_constraints.pem`` - A certificate signing request
+  for a RSA 2048 bit key containing two basic constraints extensions.
+* ``unsupported_extension.pem`` - A certificate signing request
+  for an RSA 2048 bit key containing containing an unsupported
+  extension type. The OID was encoded as "1.2.3.4" with an
+  ``extnValue`` of "value".
+* ``unsupported_extension_critical.pem`` - A certificate signing
+  request for an RSA 2048 bit key containing containing an unsupported
+  extension type marked critical. The OID was encoded as "1.2.3.4"
+  with an ``extnValue`` of "value".
 
 Hashes
 ~~~~~~
diff --git a/vectors/cryptography_vectors/x509/requests/two_basic_constraints.pem b/vectors/cryptography_vectors/x509/requests/two_basic_constraints.pem
new file mode 100644
index 0000000..da23c06
--- /dev/null
+++ b/vectors/cryptography_vectors/x509/requests/two_basic_constraints.pem
@@ -0,0 +1,66 @@
+Certificate Request:
+    Data:
+        Version: 2 (0x2)
+        Subject: C=US, ST=Texas, L=Austin, O=PyCA, CN=cryptography.io
+        Subject Public Key Info:
+            Public Key Algorithm: rsaEncryption
+            RSA Public Key: (2048 bit)
+                Modulus (2048 bit):
+                    00:cc:72:54:2d:83:be:73:f5:9a:60:3f:b8:bd:78:
+                    7d:f4:3d:6e:31:38:a9:26:72:86:19:14:87:0d:f4:
+                    68:97:19:2f:d7:7c:80:45:ad:38:27:59:db:57:76:
+                    a5:f3:b1:5e:34:5f:43:63:e5:24:0a:0f:c6:ab:39:
+                    69:d1:1a:87:68:8c:98:02:3a:08:1c:25:d7:65:30:
+                    c3:b6:a9:fa:df:ca:9d:4b:4c:b3:00:a7:fa:ea:de:
+                    ad:99:d2:67:5f:c4:15:0d:b3:70:4d:b2:0a:a7:dd:
+                    35:67:35:b9:4f:a8:b2:f6:a6:22:26:b6:ae:e8:ed:
+                    2d:e7:82:7e:a5:f2:2c:05:d5:03:5a:2e:1e:d0:62:
+                    79:04:55:4b:b3:99:94:8b:9f:6a:5e:ee:6e:b3:d4:
+                    f0:d4:9a:82:ce:e3:f4:81:5c:b2:db:24:85:b8:e4:
+                    1c:6f:a8:3d:4e:91:27:6a:fe:48:29:f2:09:40:9e:
+                    a1:e2:34:41:18:29:ce:f5:24:11:d9:22:2f:6f:94:
+                    cf:22:4e:ba:f2:38:90:00:70:d5:86:d4:6d:c2:ce:
+                    6c:32:74:75:df:f1:1f:c9:a0:be:43:2b:84:34:db:
+                    34:2f:d3:15:8f:ff:85:62:40:79:d3:3c:04:a2:b8:
+                    43:34:ae:c2:3e:1d:ad:c0:4b:28:34:c2:6d:7e:e2:
+                    9f:75
+                Exponent: 65537 (0x10001)
+        Attributes:
+        Requested Extensions:
+            X509v3 Basic Constraints: critical
+                CA:FALSE
+            X509v3 Basic Constraints: critical
+                CA:FALSE
+    Signature Algorithm: sha1WithRSAEncryption
+        b8:00:de:3c:28:bf:56:9a:a7:8f:50:a3:86:a3:02:91:8b:97:
+        1c:b8:73:81:c2:fd:85:d7:6f:ba:b1:c3:18:8a:17:d9:66:cd:
+        b9:9a:9c:1f:c8:0b:88:33:b7:4e:97:b2:60:43:ea:13:57:13:
+        17:7c:23:7d:22:6e:65:b0:0a:bc:dc:12:ec:b3:85:2f:1b:c9:
+        ef:9c:19:f3:15:fd:78:89:a6:d1:2d:b8:bf:b6:17:b8:dc:b5:
+        7a:e6:2a:4d:2c:da:01:10:31:96:12:13:49:08:1b:d9:ba:97:
+        54:e4:21:b8:50:92:9d:1f:30:f0:a2:de:99:8e:da:0e:1f:84:
+        d4:22:2a:f6:d4:3b:43:81:25:ca:2a:e2:17:f6:ef:2f:db:df:
+        67:dc:0f:1b:36:ac:46:b4:39:3b:d6:17:1a:12:fb:5f:1d:28:
+        db:9f:66:38:64:b7:43:ab:84:49:11:3b:ae:f1:30:cf:79:7e:
+        a6:52:ff:91:cb:9c:53:09:44:89:83:cf:04:7b:3c:12:7b:8f:
+        56:e7:48:9a:e5:2a:f3:1f:93:ec:07:5f:1d:f1:6d:59:ed:5e:
+        f6:6a:be:63:60:02:f4:65:34:fb:dc:0a:1b:b3:99:b5:4b:4f:
+        66:55:35:d3:79:85:48:7e:ca:0e:06:0f:92:00:27:93:79:ce:
+        f7:2f:ad:2b
+-----BEGIN CERTIFICATE REQUEST-----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-----END CERTIFICATE REQUEST-----
diff --git a/vectors/cryptography_vectors/x509/requests/unsupported_extension.pem b/vectors/cryptography_vectors/x509/requests/unsupported_extension.pem
new file mode 100644
index 0000000..d96097c
--- /dev/null
+++ b/vectors/cryptography_vectors/x509/requests/unsupported_extension.pem
@@ -0,0 +1,64 @@
+Certificate Request:
+    Data:
+        Version: 2 (0x2)
+        Subject: C=US, ST=Texas, L=Austin, O=PyCA, CN=cryptography.io
+        Subject Public Key Info:
+            Public Key Algorithm: rsaEncryption
+            RSA Public Key: (2048 bit)
+                Modulus (2048 bit):
+                    00:b6:64:25:bd:fc:ba:bf:7b:ee:da:a6:25:79:75:
+                    59:59:cb:bc:da:eb:22:66:97:93:4d:f0:67:39:45:
+                    01:5c:58:0a:17:88:e4:05:14:c8:3f:33:39:5f:a0:
+                    ca:fc:dd:28:3e:b1:d1:0d:87:c1:65:22:21:d3:4a:
+                    5c:f0:b6:4f:49:83:90:b1:88:47:b5:7f:7e:4f:34:
+                    ae:51:a5:ee:fb:92:68:2d:0f:83:86:cb:8e:e7:1d:
+                    ba:f4:6a:f2:ab:81:aa:fc:a4:05:fd:fd:07:88:59:
+                    6a:b7:c7:f5:df:92:e6:fd:ec:e7:a7:6f:ac:02:95:
+                    b7:3f:01:39:82:8e:94:84:18:cf:07:1b:25:5e:94:
+                    56:ec:2e:b7:37:71:ba:09:d2:ef:a3:46:ec:38:34:
+                    1d:0f:f8:d1:1f:4f:11:bd:03:9e:c9:46:65:f7:6d:
+                    80:2d:32:5e:44:6f:e3:21:ec:c2:76:32:62:c2:9e:
+                    47:03:27:8b:ba:49:01:2b:61:1f:6d:7b:3c:05:11:
+                    84:bd:a8:bd:44:e2:30:1e:c2:19:fc:9c:60:79:29:
+                    b9:62:92:97:94:d2:f7:30:84:b6:51:af:f1:9a:61:
+                    80:2e:f8:94:22:f7:73:32:20:79:b1:bf:ea:2d:20:
+                    20:48:51:3d:f1:51:03:b1:02:90:74:46:cf:3b:4e:
+                    f8:4b
+                Exponent: 65537 (0x10001)
+        Attributes:
+        Requested Extensions:
+            1.2.3.4: 
+                value
+    Signature Algorithm: sha1WithRSAEncryption
+        16:5f:86:90:13:fd:63:e6:c9:ca:74:68:b4:6e:e6:c5:c3:46:
+        c1:26:bc:64:2b:fc:ef:be:ab:eb:8b:a9:de:8d:4e:a8:f9:f0:
+        3e:b0:0b:8c:e4:f8:0b:28:5b:13:0c:46:f8:3b:55:cb:cc:cb:
+        ed:6a:4f:16:3a:4b:e9:65:2d:3c:1a:a5:1f:a8:07:ab:22:ee:
+        91:60:f1:06:76:0c:6e:8f:7b:25:36:4b:d6:60:04:77:e6:35:
+        10:4f:eb:fc:2a:c3:71:e5:cb:9f:94:bd:6c:44:08:79:fb:b2:
+        a0:f5:f2:c0:79:b0:c4:22:ec:81:29:b3:97:e5:2f:1f:47:c5:
+        1a:3f:be:50:c8:f4:29:9a:94:1d:19:a9:e2:d6:06:ca:07:43:
+        6c:f1:e4:7e:fb:b8:70:0c:5b:41:c4:10:84:29:39:49:17:09:
+        d1:21:89:d7:c8:e5:6c:48:66:98:ac:8b:33:ab:da:1f:51:a9:
+        2f:4c:39:6d:48:d9:7b:34:7f:b5:1e:9e:b8:87:8b:21:13:41:
+        d4:53:64:c1:16:e0:a8:c1:6f:dc:be:8f:67:ad:e6:30:79:af:
+        bf:7e:ff:64:99:50:d8:4c:58:66:9c:da:d1:53:06:2e:d3:82:
+        e3:2d:b3:65:71:6e:6a:67:cf:e1:96:4f:f7:ac:0b:2e:6e:28:
+        a4:df:f5:e6
+-----BEGIN CERTIFICATE REQUEST-----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+-----END CERTIFICATE REQUEST-----
diff --git a/vectors/cryptography_vectors/x509/requests/unsupported_extension_critical.pem b/vectors/cryptography_vectors/x509/requests/unsupported_extension_critical.pem
new file mode 100644
index 0000000..2ae17d8
--- /dev/null
+++ b/vectors/cryptography_vectors/x509/requests/unsupported_extension_critical.pem
@@ -0,0 +1,64 @@
+Certificate Request:
+    Data:
+        Version: 2 (0x2)
+        Subject: C=US, ST=Texas, L=Austin, O=PyCA, CN=cryptography.io
+        Subject Public Key Info:
+            Public Key Algorithm: rsaEncryption
+            RSA Public Key: (2048 bit)
+                Modulus (2048 bit):
+                    00:ce:ed:18:2c:b8:63:f6:65:50:1e:ec:7e:7b:86:
+                    56:25:3e:3d:5d:86:6e:9a:d1:56:b0:79:b7:85:c9:
+                    14:23:4d:ff:10:c7:68:f2:00:b6:57:39:a6:5d:3f:
+                    ed:50:67:cd:bd:da:fb:68:a9:0f:79:a9:0e:79:23:
+                    62:d0:d1:27:96:f2:d6:36:b9:6d:4e:d6:4e:0f:32:
+                    88:9b:0b:90:98:31:00:fa:2e:ca:ac:82:e3:c3:60:
+                    1c:8e:f1:be:0d:1e:bc:b6:f7:a7:9b:60:aa:4b:9a:
+                    a5:04:b5:a0:a8:29:0b:21:af:2c:40:26:87:75:85:
+                    3c:00:38:4d:a4:f9:25:8e:d5:d7:11:b4:dd:3c:27:
+                    11:0c:1c:1c:86:63:35:66:d6:47:73:6c:bd:00:03:
+                    2b:4a:d0:90:db:8c:e8:b4:8d:2a:ff:90:8f:0b:c8:
+                    32:ed:b3:23:7f:ce:01:74:26:f6:84:e6:53:54:44:
+                    45:e8:53:20:54:ec:00:6d:60:13:2b:bb:da:fe:19:
+                    82:db:a6:6c:72:fb:be:26:d2:9d:03:fd:7f:72:94:
+                    06:4e:25:d3:17:12:c5:2b:d6:a5:e1:29:3c:7b:d7:
+                    da:da:89:bf:a9:09:41:ab:73:fb:8d:8b:3f:83:4b:
+                    f1:bb:2b:5f:c6:a9:03:e6:c9:0a:fc:0a:f4:82:e1:
+                    4b:97
+                Exponent: 65537 (0x10001)
+        Attributes:
+        Requested Extensions:
+            1.2.3.4: critical
+                value
+    Signature Algorithm: sha1WithRSAEncryption
+        2c:70:0f:a6:d0:0d:70:24:a8:94:ad:4b:1d:50:46:19:7c:c0:
+        a8:fb:01:84:3b:3b:7e:b0:6f:6b:d9:86:81:a3:d4:03:e9:d7:
+        0c:f6:ff:c6:43:00:88:59:7b:bc:8f:6d:3d:46:4d:a1:0b:40:
+        ba:7e:13:4e:4f:1d:02:35:e4:5b:30:a0:a8:fc:4d:49:a5:1b:
+        11:19:57:25:58:57:03:09:55:56:cb:50:94:54:f9:15:a3:de:
+        ab:96:0d:b8:98:9d:0f:c7:16:e1:d6:0b:3b:7a:a2:53:07:d2:
+        3c:f7:89:62:66:a4:34:39:c9:03:35:2b:a5:27:69:94:7d:56:
+        dc:72:8c:bc:3a:33:15:86:f8:c3:19:bb:c2:1d:51:3e:a9:1c:
+        5c:8b:7a:63:18:1b:78:57:f4:14:be:39:90:38:d1:b6:8d:e1:
+        45:63:1e:e1:32:54:3e:52:e9:5d:4d:d5:3c:65:b1:21:e3:00:
+        88:f4:28:f7:34:f4:ac:08:54:59:4d:7b:b5:f4:84:d0:66:df:
+        98:10:a3:38:bd:2c:e2:fa:87:7c:3f:c8:36:e6:a5:e1:b9:00:
+        7d:c0:3a:40:69:b2:df:f9:c0:af:9f:e3:c6:48:a6:b6:69:0f:
+        e2:9e:36:dd:e8:ee:02:a1:10:1e:78:e6:c6:c3:b4:12:21:2d:
+        70:4c:c0:b4
+-----BEGIN CERTIFICATE REQUEST-----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+-----END CERTIFICATE REQUEST-----