diff --git a/core/src/err/mod.rs b/core/src/err/mod.rs
index 58db059f..526f3855 100644
--- a/core/src/err/mod.rs
+++ b/core/src/err/mod.rs
@@ -1103,6 +1103,9 @@ pub enum Error {
 	/// There was an outdated storage version stored in the database
 	#[error("The data stored on disk is out-of-date with this version. Please follow the upgrade guides in the documentation")]
 	OutdatedStorageVersion,
+
+	#[error("Found a non-computed value where they are not allowed")]
+	NonComputed,
 }
 
 impl From<Error> for String {
diff --git a/core/src/iam/signin.rs b/core/src/iam/signin.rs
index 87f7209d..b426066a 100644
--- a/core/src/iam/signin.rs
+++ b/core/src/iam/signin.rs
@@ -21,6 +21,8 @@ use subtle::ConstantTimeEq;
 use uuid::Uuid;
 
 pub async fn signin(kvs: &Datastore, session: &mut Session, vars: Object) -> Result<String, Error> {
+	// Check vars contains only computed values
+	vars.validate_computed()?;
 	// Parse the specified variables
 	let ns = vars.get("NS").or_else(|| vars.get("ns"));
 	let db = vars.get("DB").or_else(|| vars.get("db"));
diff --git a/core/src/iam/signup.rs b/core/src/iam/signup.rs
index b83dfb87..15cd11ff 100644
--- a/core/src/iam/signup.rs
+++ b/core/src/iam/signup.rs
@@ -19,6 +19,8 @@ pub async fn signup(
 	session: &mut Session,
 	vars: Object,
 ) -> Result<Option<String>, Error> {
+	// Check vars contains only computed values
+	vars.validate_computed()?;
 	// Parse the specified variables
 	let ns = vars.get("NS").or_else(|| vars.get("ns"));
 	let db = vars.get("DB").or_else(|| vars.get("db"));
diff --git a/core/src/sql/array.rs b/core/src/sql/array.rs
index ae13f50a..04fec8f6 100644
--- a/core/src/sql/array.rs
+++ b/core/src/sql/array.rs
@@ -168,6 +168,11 @@ impl Array {
 	pub(crate) fn is_static(&self) -> bool {
 		self.iter().all(Value::is_static)
 	}
+
+	/// Validate that an Array contains only computed Values
+	pub fn validate_computed(&self) -> Result<(), Error> {
+		self.iter().try_for_each(|v| v.validate_computed())
+	}
 }
 
 impl Display for Array {
diff --git a/core/src/sql/object.rs b/core/src/sql/object.rs
index 7eb39c4d..dedf491a 100644
--- a/core/src/sql/object.rs
+++ b/core/src/sql/object.rs
@@ -235,6 +235,11 @@ impl Object {
 	pub(crate) fn is_static(&self) -> bool {
 		self.values().all(Value::is_static)
 	}
+
+	/// Validate that a Object contains only computed Values
+	pub(crate) fn validate_computed(&self) -> Result<(), Error> {
+		self.values().try_for_each(|v| v.validate_computed())
+	}
 }
 
 impl Display for Object {
diff --git a/core/src/sql/range.rs b/core/src/sql/range.rs
index 1dee74d3..7c3159d9 100644
--- a/core/src/sql/range.rs
+++ b/core/src/sql/range.rs
@@ -115,6 +115,20 @@ impl Range {
 			},
 		})))
 	}
+
+	/// Validate that a Range contains only computed Values
+	pub fn validate_computed(&self) -> Result<(), Error> {
+		match &self.beg {
+			Bound::Included(ref v) | Bound::Excluded(ref v) => v.validate_computed()?,
+			Bound::Unbounded => {}
+		}
+		match &self.end {
+			Bound::Included(ref v) | Bound::Excluded(ref v) => v.validate_computed()?,
+			Bound::Unbounded => {}
+		}
+
+		Ok(())
+	}
 }
 
 impl PartialOrd for Range {
diff --git a/core/src/sql/value/value.rs b/core/src/sql/value/value.rs
index a9e32950..af05eeed 100644
--- a/core/src/sql/value/value.rs
+++ b/core/src/sql/value/value.rs
@@ -2890,6 +2890,21 @@ impl InfoStructure for Value {
 	}
 }
 
+impl Value {
+	/// Validate that a Value is computed or contains only computed Values
+	pub fn validate_computed(&self) -> Result<(), Error> {
+		use Value::*;
+		match self {
+			None | Null | Bool(_) | Number(_) | Strand(_) | Duration(_) | Datetime(_) | Uuid(_)
+			| Geometry(_) | Bytes(_) | Thing(_) => Ok(()),
+			Array(a) => a.validate_computed(),
+			Object(o) => o.validate_computed(),
+			Range(r) => r.validate_computed(),
+			_ => Err(Error::NonComputed),
+		}
+	}
+}
+
 impl Value {
 	/// Check if we require a writeable transaction
 	pub(crate) fn writeable(&self) -> bool {
diff --git a/tests/http_integration.rs b/tests/http_integration.rs
index 105baa2b..e824d49e 100644
--- a/tests/http_integration.rs
+++ b/tests/http_integration.rs
@@ -9,6 +9,7 @@ mod http_integration {
 	use reqwest::Client;
 	use serde_json::json;
 	use surrealdb::headers::{AUTH_DB, AUTH_NS};
+	use surrealdb::sql;
 	use test_log::test;
 	use ulid::Ulid;
 
@@ -1727,4 +1728,80 @@ mod http_integration {
 
 		Ok(())
 	}
+
+	#[test(tokio::test)]
+	async fn signup_mal() -> Result<(), Box<dyn std::error::Error>> {
+		let (addr, _server) = common::start_server_with_defaults().await.unwrap();
+		let rpc_url = &format!("http://{addr}/rpc");
+
+		let ns = Ulid::new().to_string();
+		let db = Ulid::new().to_string();
+
+		// Prepare HTTP client
+		let mut headers = reqwest::header::HeaderMap::new();
+		headers.insert("surreal-ns", ns.parse()?);
+		headers.insert("surreal-db", db.parse()?);
+		headers.insert(header::ACCEPT, "application/surrealdb".parse()?);
+		headers.insert(header::CONTENT_TYPE, "application/surrealdb".parse()?);
+		let client = reqwest::Client::builder()
+			.connect_timeout(Duration::from_millis(10))
+			.default_headers(headers)
+			.build()?;
+
+		// Define a record access method
+		{
+			let res = client
+				.post(format!("http://{addr}/sql"))
+				.basic_auth(USER, Some(PASS))
+				.body(
+					r#"
+					DEFINE ACCESS user ON DATABASE TYPE RECORD
+						SIGNUP ( CREATE user SET email = $email, pass = crypto::argon2::generate($pass) )
+						SIGNIN ( SELECT * FROM user WHERE email = $email AND crypto::argon2::compare(pass, $pass) )
+						DURATION FOR SESSION 12h
+					;
+				"#,
+				)
+				.send()
+				.await?;
+			assert!(res.status().is_success(), "body: {}", res.text().await?);
+		}
+
+		{
+			let mut request = sql::Object::default();
+			request.insert("method".to_string(), "signup".into());
+
+			let stmt: sql::Statement = {
+				let mut tmp = sql::statements::CreateStatement::default();
+				let rid = sql::thing("foo:42").unwrap();
+				let mut tmp_values = sql::Values::default();
+				tmp_values.0 = vec![rid.into()];
+				tmp.what = tmp_values;
+				sql::Statement::Create(tmp)
+			};
+
+			let mut obj = sql::Object::default();
+			obj.insert("email".to_string(), sql::Value::Query(stmt.into()));
+			obj.insert("pass".to_string(), "foo".into());
+			request.insert(
+				"params".to_string(),
+				sql::Value::Array(vec![sql::Value::Object(obj)].into()),
+			);
+
+			let req: sql::Value = sql::Value::Object(request);
+
+			let req = sql::serde::serialize(&req).unwrap();
+
+			let res = client.post(rpc_url).body(req).send().await?;
+
+			let body = res.text().await?;
+
+			assert!(
+				body.contains("Found a non-computed value where they are not allowed"),
+				"{body:?}"
+			);
+		}
+
+		Ok(())
+	}
 }