diff --git a/ChangeLog b/ChangeLog
index 6ec00d366..87b818532 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -30,6 +30,9 @@ Bugfix
    * Fixed the sample applications gen_key.c, cert_req.c and cert_write.c for
      builds where the configuration MBEDTLS_PEM_WRITE_C is not defined. Found
      by inestlerode. #559.
+   * Fix mbedtls_x509_get_sig() to update the ASN1 type in the mbedtls_x509_buf
+     data structure until after error checks are successful. Found by
+     subramanyam-c. #622
    * Fix documentation and implementation missmatch for function arguments of
      mbedtls_gcm_finish(). Found by cmiatpaar. #602
    * Guarantee that P>Q at RSA key generation. Found by inestlerode. #558
@@ -37,6 +40,10 @@ Bugfix
      result in usage of invalid md_ctx in mbedtls_rsa_rsaes_oaep_encrypt(),
      mbedtls_rsa_rsaes_oaep_decrypt(), mbedtls_rsa_rsassa_pss_sign() and
      mbedtls_rsa_rsassa_pss_verify_ext(). Fixed by Brian J. Murray. #502
+   * Fix potential byte overread when verifying malformed SERVER_HELLO in
+     ssl_parse_hello_verify_request() for DTLS. Found by Guido Vranken.
+   * Fix check for validity of date when parsing in mbedtls_x509_get_time().
+     Found by subramanyam-c. #626
 
 = mbed TLS 2.1.5 branch released 2016-06-28
 
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 16fd43b71..3d7283c3d 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1226,6 +1226,15 @@ static int ssl_parse_hello_verify_request( mbedtls_ssl_context *ssl )
     cookie_len = *p++;
     MBEDTLS_SSL_DEBUG_BUF( 3, "cookie", p, cookie_len );
 
+    if( ( ssl->in_msg + ssl->in_msglen ) - p < cookie_len )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "cookie length does not match incoming message size" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
     mbedtls_free( ssl->handshake->verify_cookie );
 
     ssl->handshake->verify_cookie = mbedtls_calloc( 1, cookie_len );
diff --git a/library/x509.c b/library/x509.c
index ffc3d6c94..33bcb9ef0 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -75,6 +75,7 @@
 #endif
 
 #define CHECK(code) if( ( ret = code ) != 0 ){ return( ret ); }
+#define CHECK_RANGE(min, max, val) if( val < min || val > max ){ return( ret ); }
 
 /*
  *  CertificateSerialNumber  ::=  INTEGER
@@ -484,6 +485,33 @@ static int x509_parse_int(unsigned char **p, unsigned n, int *res){
     return 0;
 }
 
+static int x509_date_is_valid(const mbedtls_x509_time *time)
+{
+    int ret = MBEDTLS_ERR_X509_INVALID_DATE;
+
+    CHECK_RANGE( 0, 9999, time->year );
+    CHECK_RANGE( 0, 23,   time->hour );
+    CHECK_RANGE( 0, 59,   time->min  );
+    CHECK_RANGE( 0, 59,   time->sec  );
+
+    switch( time->mon )
+    {
+        case 1: case 3: case 5: case 7: case 8: case 10: case 12:
+            CHECK_RANGE( 1, 31, time->day );
+            break;
+        case 4: case 6: case 9: case 11:
+            CHECK_RANGE( 1, 30, time->day );
+            break;
+        case 2:
+            CHECK_RANGE( 1, 28 + (time->year % 4 == 0), time->day );
+            break;
+        default:
+            return( ret );
+    }
+
+    return( 0 );
+}
+
 /*
  *  Time ::= CHOICE {
  *       utcTime        UTCTime,
@@ -523,6 +551,8 @@ int mbedtls_x509_get_time( unsigned char **p, const unsigned char *end,
         time->year +=  100 * ( time->year < 50 );
         time->year += 1900;
 
+        CHECK( x509_date_is_valid( time ) );
+
         return( 0 );
     }
     else if( tag == MBEDTLS_ASN1_GENERALIZED_TIME )
@@ -543,6 +573,8 @@ int mbedtls_x509_get_time( unsigned char **p, const unsigned char *end,
         if( len > 14 && *(*p)++ != 'Z' )
             return( MBEDTLS_ERR_X509_INVALID_DATE );
 
+        CHECK( x509_date_is_valid( time ) );
+
         return( 0 );
     }
     else
@@ -554,16 +586,18 @@ int mbedtls_x509_get_sig( unsigned char **p, const unsigned char *end, mbedtls_x
 {
     int ret;
     size_t len;
+    int tag_type;
 
     if( ( end - *p ) < 1 )
         return( MBEDTLS_ERR_X509_INVALID_SIGNATURE +
                 MBEDTLS_ERR_ASN1_OUT_OF_DATA );
 
-    sig->tag = **p;
+    tag_type = **p;
 
     if( ( ret = mbedtls_asn1_get_bitstring_null( p, end, &len ) ) != 0 )
         return( MBEDTLS_ERR_X509_INVALID_SIGNATURE + ret );
 
+    sig->tag = tag_type;
     sig->len = len;
     sig->p = *p;
 
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index 5c68872c0..6511cef9f 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -1476,3 +1476,39 @@ x509parse_crt_file:"data_files/server7_all_space.crt":MBEDTLS_ERR_PEM_INVALID_DA
 X509 File parse (trailing spaces, OK)
 depends_on:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
 x509parse_crt_file:"data_files/server7_trailing_space.crt":0
+
+X509 Get time (UTC no issues)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"500101000000Z":0:1950:1:1:0:0:0
+
+X509 Get time (Generalized Time no issues)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_GENERALIZED_TIME:"99991231235959Z":0:9999:12:31:23:59:59
+
+X509 Get time (UTC year without leap day)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"490229121212Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
+
+X509 Get time (UTC year with leap day)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"000229121212Z":0:2000:2:29:12:12:12
+
+X509 Get time (UTC invalid day of month #1)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"000132121212Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
+
+X509 Get time (UTC invalid day of month #2)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"001131121212Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
+
+X509 Get time (UTC invalid hour)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"001130241212Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
+
+X509 Get time (UTC invalid min)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"001130236012Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
+
+X509 Get time (UTC invalid sec)
+depends_on:MBEDTLS_X509_USE_C
+x509_get_time:MBEDTLS_ASN1_UTC_TIME:"001130235960Z":MBEDTLS_ERR_X509_INVALID_DATE:0:0:0:0:0:0
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index c476ec507..40e653d1d 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -1,4 +1,5 @@
 /* BEGIN_HEADER */
+#include "mbedtls/x509.h"
 #include "mbedtls/x509_crt.h"
 #include "mbedtls/x509_crl.h"
 #include "mbedtls/x509_csr.h"
@@ -590,6 +591,39 @@ exit:
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_X509_USE_C */
+void x509_get_time( int tag,  char *time_str, int ret,
+                    int year, int mon, int day,
+                    int hour, int min, int sec )
+{
+    mbedtls_x509_time time;
+    unsigned char buf[17];
+    unsigned char* start = buf;
+    unsigned char* end = buf;
+
+    memset( &time, 0x00, sizeof( time ) );
+    *end = (unsigned char)tag; end++;
+    if( tag == MBEDTLS_ASN1_UTC_TIME )
+        *end = 13;
+    else
+        *end = 15;
+    end++;
+    memcpy( end, time_str, (size_t)*(end - 1) );
+    end += *(end - 1);
+
+    TEST_ASSERT( mbedtls_x509_get_time( &start, end, &time ) == ret );
+    if( ret == 0 )
+    {
+        TEST_ASSERT( year == time.year );
+        TEST_ASSERT( mon  == time.mon  );
+        TEST_ASSERT( day  == time.day  );
+        TEST_ASSERT( hour == time.hour );
+        TEST_ASSERT( min  == time.min  );
+        TEST_ASSERT( sec  == time.sec  );
+    }
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C:MBEDTLS_X509_RSASSA_PSS_SUPPORT */
 void x509_parse_rsassa_pss_params( char *hex_params, int params_tag,
                                    int ref_msg_md, int ref_mgf_md,