diff --git a/library/cipher.c b/library/cipher.c
index 5edc39a..495bd51 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -185,11 +185,21 @@
     if( NULL == ctx || NULL == ctx->cipher_info || NULL == iv )
         return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
 
+    /* avoid buffer overflow in ctx->iv */
+    if( iv_len > POLARSSL_MAX_IV_LENGTH )
+        return POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE;
+
     if( ctx->cipher_info->accepts_variable_iv_size )
         actual_iv_size = iv_len;
     else
+    {
         actual_iv_size = ctx->cipher_info->iv_size;
 
+        /* avoid reading past the end of input buffer */
+        if( actual_iv_size > iv_len )
+            return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
+    }
+
     memcpy( ctx->iv, iv, actual_iv_size );
     ctx->iv_size = actual_iv_size;