diff --git a/src/db_auc.c b/src/db_auc.c
index e29b44b..2cf7143 100644
--- a/src/db_auc.c
+++ b/src/db_auc.c
@@ -73,6 +73,32 @@
 	return ret;
 }
 
+/* hexparse a specific column of a sqlite prepared statement into dst (with length check)
+ * returns 0 for success, -EIO on error */
+static int hexparse_stmt(uint8_t *dst, size_t dst_len, sqlite3_stmt *stmt, int col, const char *col_name,
+			 const char *imsi)
+{
+	const uint8_t *text;
+	size_t col_len;
+
+	/* Bytes are stored as hex strings in database, hence divide length by two */
+	col_len = sqlite3_column_bytes(stmt, col) / 2;
+
+	if (col_len != dst_len) {
+		LOGAUC(imsi, LOGL_ERROR, "Error reading %s, expected length %lu but has length %lu\n", col_name,
+		       dst_len, col_len);
+		return -EIO;
+	}
+
+	text = sqlite3_column_text(stmt, col);
+	if (!text) {
+		LOGAUC(imsi, LOGL_ERROR, "Error reading %s\n", col_name);
+		return -EIO;
+	}
+	osmo_hexparse((void *)text, dst, dst_len);
+	return 0;
+}
+
 /* obtain the authentication data for a given imsi
  * returns 0 for success, negative value on error:
  * -ENOENT if the IMSI is not known, -ENOKEY if the IMSI is known but has no auth data,
@@ -113,49 +139,34 @@
 	/* obtain result values using sqlite3_column_*() */
 	if (sqlite3_column_type(stmt, 1) == SQLITE_INTEGER) {
 		/* we do have some 2G authentication data */
-		const uint8_t *ki;
-
-		aud2g->algo = sqlite3_column_int(stmt, 1);
-		ki = sqlite3_column_text(stmt, 2);
-#if 0
-		if (sqlite3_column_bytes(stmt, 2) != sizeof(aud2g->u.gsm.ki)) {
-			LOGAUC(imsi, LOGL_ERROR, "Error reading Ki: %d\n", rc);
+		if (hexparse_stmt(aud2g->u.gsm.ki, sizeof(aud2g->u.gsm.ki), stmt, 2, "Ki", imsi))
 			goto end_2g;
-		}
-#endif
-		osmo_hexparse((void*)ki, (void*)&aud2g->u.gsm.ki, sizeof(aud2g->u.gsm.ki));
+		aud2g->algo = sqlite3_column_int(stmt, 1);
 		aud2g->type = OSMO_AUTH_TYPE_GSM;
 	} else
 		LOGAUC(imsi, LOGL_DEBUG, "No 2G Auth Data\n");
-//end_2g:
+end_2g:
 	if (sqlite3_column_type(stmt, 3) == SQLITE_INTEGER) {
 		/* we do have some 3G authentication data */
-		const uint8_t *k, *op, *opc;
-
-		aud3g->algo = sqlite3_column_int(stmt, 3);
-		k = sqlite3_column_text(stmt, 4);
-		if (!k) {
-			LOGAUC(imsi, LOGL_ERROR, "Error reading K: %d\n", rc);
+		if (hexparse_stmt(aud3g->u.umts.k, sizeof(aud3g->u.umts.k), stmt, 4, "K", imsi)) {
 			ret = -EIO;
 			goto out;
 		}
-		osmo_hexparse((void*)k, (void*)&aud3g->u.umts.k, sizeof(aud3g->u.umts.k));
+		aud3g->algo = sqlite3_column_int(stmt, 3);
+
 		/* UMTS Subscribers can have either OP or OPC */
-		op = sqlite3_column_text(stmt, 5);
-		if (!op) {
-			opc = sqlite3_column_text(stmt, 6);
-			if (!opc) {
-				LOGAUC(imsi, LOGL_ERROR, "Error reading OPC: %d\n", rc);
+		if (sqlite3_column_text(stmt, 5)) {
+			if (hexparse_stmt(aud3g->u.umts.opc, sizeof(aud3g->u.umts.opc), stmt, 5, "OP", imsi)) {
 				ret = -EIO;
 				goto out;
 			}
-			osmo_hexparse((void*)opc, (void*)&aud3g->u.umts.opc,
-					sizeof(aud3g->u.umts.opc));
-			aud3g->u.umts.opc_is_op = 0;
-		} else {
-			osmo_hexparse((void*)op, (void*)&aud3g->u.umts.opc,
-					sizeof(aud3g->u.umts.opc));
 			aud3g->u.umts.opc_is_op = 1;
+		} else {
+			if (hexparse_stmt(aud3g->u.umts.opc, sizeof(aud3g->u.umts.opc), stmt, 6, "OPC", imsi)) {
+				ret = -EIO;
+				goto out;
+			}
+			aud3g->u.umts.opc_is_op = 0;
 		}
 		aud3g->u.umts.sqn = sqlite3_column_int64(stmt, 7);
 		aud3g->u.umts.ind_bitlen = sqlite3_column_int(stmt, 8);
diff --git a/tests/db/db_test.c b/tests/db/db_test.c
index fdd62c5..cc299bf 100644
--- a/tests/db/db_test.c
+++ b/tests/db/db_test.c
@@ -208,6 +208,17 @@
 #undef Phex
 }
 
+void db_raw_sql(struct db_context *dbc, const char *sql)
+{
+	sqlite3_stmt *stmt;
+
+	fprintf(stderr, "raw SQL: %s\n", sql);
+	ASSERT_RC(sqlite3_prepare_v2(dbc->db, sql, -1, &stmt, NULL), SQLITE_OK);
+	ASSERT_RC(sqlite3_step(stmt), SQLITE_DONE);
+	db_remove_reset(stmt);
+	sqlite3_finalize(stmt);
+}
+
 static const char *imsi0 = "123456789000000";
 static const char *imsi1 = "123456789000001";
 static const char *imsi2 = "123456789000002";
@@ -749,6 +760,70 @@
 	comment_end();
 }
 
+/* Make each key too short in this test. Note that we can't set them longer than the allowed size without changing the
+ * table structure. */
+static void test_subscr_aud_invalid_len()
+{
+	int64_t id;
+
+	comment_start();
+	comment("Create subscriber");
+	ASSERT_RC(db_subscr_create(dbc, imsi0, DB_SUBSCR_FLAG_NAM_CS | DB_SUBSCR_FLAG_NAM_PS), 0);
+	ASSERT_SEL(imsi, imsi0, 0);
+	id = g_subscr.id;
+
+
+	/* Invalid Ki length */
+	comment("Set auth data, 2G only, with invalid Ki length");
+	ASSERT_RC(db_subscr_update_aud_by_id(dbc, id,
+		  mk_aud_2g(OSMO_AUTH_ALG_COMP128v1, "0123456789abcdef0123456789abcdef")),
+		  0);
+	/* Use raw SQL to avoid length check in db_subscr_update_aud_by_id(). This changes all rows in the table, which
+         * is fine for this test (implicit WHERE 1). */
+	db_raw_sql(dbc, "UPDATE auc_2g SET ki = '0123456789abcdef0123456789abcde'");
+	ASSERT_SEL_AUD(imsi0, -ENOKEY, id);
+
+	comment("Remove 2G auth data");
+	ASSERT_RC(db_subscr_update_aud_by_id(dbc, id,
+		  mk_aud_2g(OSMO_AUTH_ALG_NONE, NULL)),
+		  0);
+
+	/* Invalid K length */
+	comment("Set auth data, 3G only, with invalid K length");
+	ASSERT_RC(db_subscr_update_aud_by_id(dbc, id,
+		mk_aud_3g(OSMO_AUTH_ALG_MILENAGE,
+			  "BeefedCafeFaceAcedAddedDecadeFee", true,
+			  "C01ffedC1cadaeAc1d1f1edAcac1aB0a", 5)),
+		0);
+	db_raw_sql(dbc, "UPDATE auc_3g SET k = 'C01ffedC1cadaeAc1d1f1edAcac1aB0'");
+	ASSERT_SEL_AUD(imsi0, -EIO, id);
+
+	/* Invalid OP length */
+	comment("Set auth data, 3G only, with invalid OP length");
+	ASSERT_RC(db_subscr_update_aud_by_id(dbc, id,
+		mk_aud_3g(OSMO_AUTH_ALG_MILENAGE,
+			  "BeefedCafeFaceAcedAddedDecadeFee", true,
+			  "C01ffedC1cadaeAc1d1f1edAcac1aB0a", 5)),
+		0);
+	db_raw_sql(dbc, "UPDATE auc_3g SET op = 'BeefedCafeFaceAcedAddedDecadeFe'");
+	ASSERT_SEL_AUD(imsi0, -EIO, id);
+
+	/* Invalid OPC length */
+	comment("Set auth data, 3G only, with invalid OPC length");
+	ASSERT_RC(db_subscr_update_aud_by_id(dbc, id,
+		mk_aud_3g(OSMO_AUTH_ALG_MILENAGE,
+			  "BeefedCafeFaceAcedAddedDecadeFee", false,
+			  "C01ffedC1cadaeAc1d1f1edAcac1aB0a", 5)),
+		0);
+	db_raw_sql(dbc, "UPDATE auc_3g SET opc = 'BeefedCafeFaceAcedAddedDecadeFe'");
+	ASSERT_SEL_AUD(imsi0, -EIO, id);
+
+
+	comment("Delete subscriber");
+	ASSERT_RC(db_subscr_delete_by_id(dbc, id), 0);
+	comment_end();
+}
+
 static void test_subscr_sqn()
 {
 	int64_t id;
@@ -900,6 +975,7 @@
 
 	test_subscr_create_update_sel_delete();
 	test_subscr_aud();
+	test_subscr_aud_invalid_len();
 	test_subscr_sqn();
 
 	printf("Done\n");
diff --git a/tests/db/db_test.err b/tests/db/db_test.err
index 4dc77e8..a7c4cf1 100644
--- a/tests/db/db_test.err
+++ b/tests/db/db_test.err
@@ -1338,6 +1338,91 @@
 ===== test_subscr_aud: SUCCESS
 
 
+===== test_subscr_aud_invalid_len
+
+--- Create subscriber
+
+db_subscr_create(dbc, imsi0, DB_SUBSCR_FLAG_NAM_CS | DB_SUBSCR_FLAG_NAM_PS) --> 0
+
+db_subscr_get_by_imsi(dbc, imsi0, &g_subscr) --> 0
+struct hlr_subscriber {
+  .id = 1,
+  .imsi = '123456789000000',
+}
+
+
+--- Set auth data, 2G only, with invalid Ki length
+
+db_subscr_update_aud_by_id(dbc, id, mk_aud_2g(OSMO_AUTH_ALG_COMP128v1, "0123456789abcdef0123456789abcdef")) --> 0
+
+raw SQL: UPDATE auc_2g SET ki = '0123456789abcdef0123456789abcde'
+sqlite3_prepare_v2(dbc->db, sql, -1, &stmt, NULL) --> SQLITE_OK
+
+sqlite3_step(stmt) --> SQLITE_DONE
+
+db_get_auth_data(dbc, imsi0, &g_aud2g, &g_aud3g, &g_id) --> -126
+DAUC IMSI='123456789000000': Error reading Ki, expected length 16 but has length 15
+DAUC IMSI='123456789000000': No 3G Auth Data
+
+
+
+--- Remove 2G auth data
+
+db_subscr_update_aud_by_id(dbc, id, mk_aud_2g(OSMO_AUTH_ALG_NONE, NULL)) --> 0
+
+
+--- Set auth data, 3G only, with invalid K length
+
+db_subscr_update_aud_by_id(dbc, id, mk_aud_3g(OSMO_AUTH_ALG_MILENAGE, "BeefedCafeFaceAcedAddedDecadeFee", true, "C01ffedC1cadaeAc1d1f1edAcac1aB0a", 5)) --> 0
+
+raw SQL: UPDATE auc_3g SET k = 'C01ffedC1cadaeAc1d1f1edAcac1aB0'
+sqlite3_prepare_v2(dbc->db, sql, -1, &stmt, NULL) --> SQLITE_OK
+
+sqlite3_step(stmt) --> SQLITE_DONE
+
+db_get_auth_data(dbc, imsi0, &g_aud2g, &g_aud3g, &g_id) --> -5
+DAUC IMSI='123456789000000': No 2G Auth Data
+DAUC IMSI='123456789000000': Error reading K, expected length 16 but has length 15
+
+
+
+--- Set auth data, 3G only, with invalid OP length
+
+db_subscr_update_aud_by_id(dbc, id, mk_aud_3g(OSMO_AUTH_ALG_MILENAGE, "BeefedCafeFaceAcedAddedDecadeFee", true, "C01ffedC1cadaeAc1d1f1edAcac1aB0a", 5)) --> 0
+
+raw SQL: UPDATE auc_3g SET op = 'BeefedCafeFaceAcedAddedDecadeFe'
+sqlite3_prepare_v2(dbc->db, sql, -1, &stmt, NULL) --> SQLITE_OK
+
+sqlite3_step(stmt) --> SQLITE_DONE
+
+db_get_auth_data(dbc, imsi0, &g_aud2g, &g_aud3g, &g_id) --> -5
+DAUC IMSI='123456789000000': No 2G Auth Data
+DAUC IMSI='123456789000000': Error reading OP, expected length 16 but has length 15
+
+
+
+--- Set auth data, 3G only, with invalid OPC length
+
+db_subscr_update_aud_by_id(dbc, id, mk_aud_3g(OSMO_AUTH_ALG_MILENAGE, "BeefedCafeFaceAcedAddedDecadeFee", false, "C01ffedC1cadaeAc1d1f1edAcac1aB0a", 5)) --> 0
+
+raw SQL: UPDATE auc_3g SET opc = 'BeefedCafeFaceAcedAddedDecadeFe'
+sqlite3_prepare_v2(dbc->db, sql, -1, &stmt, NULL) --> SQLITE_OK
+
+sqlite3_step(stmt) --> SQLITE_DONE
+
+db_get_auth_data(dbc, imsi0, &g_aud2g, &g_aud3g, &g_id) --> -5
+DAUC IMSI='123456789000000': No 2G Auth Data
+DAUC IMSI='123456789000000': Error reading OPC, expected length 16 but has length 15
+
+
+
+--- Delete subscriber
+
+db_subscr_delete_by_id(dbc, id) --> 0
+
+===== test_subscr_aud_invalid_len: SUCCESS
+
+
 ===== test_subscr_sqn
 
 --- Set SQN for unknown subscriber