diff --git a/packages/hydrooj/src/handler/problem.ts b/packages/hydrooj/src/handler/problem.ts
index 16408f24c..ca6bf2a0a 100644
--- a/packages/hydrooj/src/handler/problem.ts
+++ b/packages/hydrooj/src/handler/problem.ts
@@ -208,6 +208,11 @@ export class ProblemMainHandler extends Handler {
         if (!ddoc) throw new NotFoundError(target);
         const dudoc = await user.getById(target, this.user._id);
         if (!dudoc.hasPerm(PERM.PERM_CREATE_PROBLEM)) throw new PermissionError(PERM.PERM_CREATE_PROBLEM);
+        // Check if user can access all those problems
+        await problem.getList(
+            domainId, pids, this.user.hasPerm(PERM.PERM_VIEW_PROBLEM_HIDDEN) || this.user._id,
+            true, ['docId'], true,
+        );
         const ids = [];
         for (const pid of pids) {
             // eslint-disable-next-line no-await-in-loop
diff --git a/packages/hydrooj/src/model/problem.ts b/packages/hydrooj/src/model/problem.ts
index 2401995ab..2445e426b 100644
--- a/packages/hydrooj/src/model/problem.ts
+++ b/packages/hydrooj/src/model/problem.ts
@@ -396,13 +396,6 @@ export class ProblemModel {
         return indexByDocIdOnly ? r : Object.assign(r, l);
     }
 
-    static async getPrefixList(domainId: string, prefix: string) {
-        const $regex = new RegExp(`^${escapeRegExp(prefix.toLowerCase())}`, 'i');
-        const filter = { $or: [{ pid: { $regex } }, { title: { $regex } }] };
-        return await document.getMulti(domainId, document.TYPE_PROBLEM, filter, ['domainId', 'docId', 'pid', 'title'])
-            .limit(20).toArray();
-    }
-
     static async getListStatus(domainId: string, uid: number, pids: number[]) {
         const psdocs = await ProblemModel.getMultiStatus(
             domainId, { uid, docId: { $in: Array.from(new Set(pids)) } },