diff --git a/frontend/src/components/attendancemanage/AbsenceSummaryModal.jsx b/frontend/src/components/attendancemanage/AbsenceSummaryModal.jsx
index 9e6da871..29c12e09 100644
--- a/frontend/src/components/attendancemanage/AbsenceSummaryModal.jsx
+++ b/frontend/src/components/attendancemanage/AbsenceSummaryModal.jsx
@@ -1,14 +1,14 @@
-import React from 'react';
+import { createPortal } from 'react-dom';
 import styles from './AbsenceSummaryModal.module.css';
 
 const AbsenceSummaryModal = ({ isOpen, onClose, userRows }) => {
   if (!isOpen) return null;
 
   // 결석한 기록이 있는 유저들만 필터링하고 결석 횟수 계산
-  const absenceData = userRows
+  const absenceData = (userRows || [])
     .map(user => {
-      const totalAbsences = user.attendances.filter(att => att.status === 'ABSENT').length;
-      const totalLates = user.attendances.filter(att => att.status === 'LATE').length;
+      const totalAbsences = (user.attendances || []).filter(att => att.status === 'ABSENT').length;
+      const totalLates = (user.attendances || []).filter(att => att.status === 'LATE').length;
       return {
         ...user,
         totalAbsences,
@@ -18,7 +18,7 @@ const AbsenceSummaryModal = ({ isOpen, onClose, userRows }) => {
     .filter(user => user.totalAbsences > 0 || user.totalLates > 0)
     .sort((a, b) => b.totalAbsences - a.totalAbsences || b.totalLates - a.totalLates);
 
-  return (
+  const modalContent = (
     <div className={styles.modalOverlay} onClick={onClose}>
       <div
         className={styles.modalContent}
@@ -80,6 +80,8 @@ const AbsenceSummaryModal = ({ isOpen, onClose, userRows }) => {
       </div>
     </div>
   );
+
+  return createPortal(modalContent, document.body);
 };
 
 export default AbsenceSummaryModal;
diff --git a/frontend/src/components/attendancemanage/AbsenceSummaryModal.module.css b/frontend/src/components/attendancemanage/AbsenceSummaryModal.module.css
index 343a8dd8..ab2d12ad 100644
--- a/frontend/src/components/attendancemanage/AbsenceSummaryModal.module.css
+++ b/frontend/src/components/attendancemanage/AbsenceSummaryModal.module.css
@@ -67,6 +67,7 @@
   padding: 24px 28px;
   overflow-y: auto;
   flex: 1;
+  max-height: 100%;
 }
 
 .summaryTable {
@@ -75,6 +76,8 @@
 }
 
 .summaryTable th {
+  position: sticky;
+  top: -24px; /* modalBody padding-top 보정 */
   text-align: left;
   padding: 12px 14px;
   font-size: 14px;
@@ -82,6 +85,7 @@
   color: #64748b;
   background: #f8fafc;
   border-bottom: 2px solid #e2e8f0;
+  z-index: 10;
 }
 
 .summaryTable td {
diff --git a/frontend/src/components/attendancemanage/AttendanceManagementCard.jsx b/frontend/src/components/attendancemanage/AttendanceManagementCard.jsx
index 11062bde..a00352af 100644
--- a/frontend/src/components/attendancemanage/AttendanceManagementCard.jsx
+++ b/frontend/src/components/attendancemanage/AttendanceManagementCard.jsx
@@ -157,8 +157,8 @@ const AttendanceManagementCard = ({ styles: commonStyles }) => {
   const fetchRequestIdRef = useRef(0);
 
   const sortedUserRows = useMemo(() => {
-    if (!attendanceData.rounds.length) {
-      return attendanceData.userRows
+    if (!(attendanceData?.rounds || []).length) {
+      return (attendanceData?.userRows || [])
         .map((user, index) => ({ user, index }))
         .sort((a, b) => {
           const priorityDiff =
@@ -170,9 +170,9 @@ const AttendanceManagementCard = ({ styles: commonStyles }) => {
     }
 
     // 로컬 시간대 기준으로 오늘 날짜(YYYY-MM-DD)와 정렬된 회차 목록 생성
-    const sortedRounds = [...attendanceData.rounds].sort(
+    const sortedRounds = [...(attendanceData?.rounds || [])].sort(
       (a, b) =>
-        a.roundDate.localeCompare(b.roundDate) || a.roundNumber - b.roundNumber
+        (a.roundDate || '').localeCompare(b.roundDate || '') || (a.roundNumber || 0) - (b.roundNumber || 0)
     );
     const todayStr = new Date().toLocaleDateString('sv-SE');
 
@@ -181,10 +181,9 @@ const AttendanceManagementCard = ({ styles: commonStyles }) => {
       sortedRounds[sortedRounds.length - 1];
 
     const targetRoundId = targetRound?.roundId;
-
-    return [...attendanceData.userRows].sort((a, b) => {
-      const aAtt = a.attendances.find((att) => att.roundId === targetRoundId);
-      const bAtt = b.attendances.find((att) => att.roundId === targetRoundId);
+    return [...(attendanceData?.userRows || [])].sort((a, b) => {
+      const aAtt = (a?.attendances || []).find((att) => att.roundId === targetRoundId);
+      const bAtt = (b?.attendances || []).find((att) => att.roundId === targetRoundId);
 
       const aStatus = aAtt?.status || 'PENDING';
       const bStatus = bAtt?.status || 'PENDING';
@@ -513,7 +512,7 @@ const AttendanceManagementCard = ({ styles: commonStyles }) => {
               <th className={styles.nameHeader}>이름</th>
               <th className={styles.roleHeader}>역할</th>
               <th className={styles.studentIdHeader}>학번</th>
-              {attendanceData.rounds.map((round) => (
+              {(attendanceData?.rounds || []).map((round) => (
                 <th key={round.roundId} className={styles.roundHeader}>
                   {round.roundNumber}회차
                 </th>
@@ -540,7 +539,7 @@ const AttendanceManagementCard = ({ styles: commonStyles }) => {
                     <td>{user.userName}</td>
                     <td>{getRoleDisplayLabel(user.role)}</td>
                     <td>{user.studentId}</td>
-                    {user.attendances.map((att) => {
+                    {(user.attendances || []).map((att) => {
                       const statusClass =
                         styles[
                           ATTENDANCE_CONFIG[att.status]?.className ||
@@ -585,7 +584,7 @@ const AttendanceManagementCard = ({ styles: commonStyles }) => {
             ) : (
               <tr>
                 <td
-                  colSpan={4 + attendanceData.rounds.length}
+                  colSpan={4 + (attendanceData?.rounds || []).length}
                   className={styles.noData}
                 >
                   데이터가 존재하지 않습니다.
diff --git a/frontend/src/components/attendancemanage/SessionManagementCard.jsx b/frontend/src/components/attendancemanage/SessionManagementCard.jsx
index 0a3a4463..7a2f182c 100644
--- a/frontend/src/components/attendancemanage/SessionManagementCard.jsx
+++ b/frontend/src/components/attendancemanage/SessionManagementCard.jsx
@@ -77,7 +77,12 @@ const SessionManagementCard = ({ styles: commonStyles }) => {
         const rounds = await getRounds(selectedSessionId);
         setCurrentDisplayedRounds(rounds || []);
       } catch (e) {
-        toast.error('라운드를 불러오지 못했습니다.');
+        const status = e?.response?.status ?? e?.status;
+        if (status === 403) {
+          toast.error('세션 멤버가 아니거나 조회 권한이 없습니다.');
+        } else {
+          toast.error('라운드를 불러오지 못했습니다.');
+        }
         setCurrentDisplayedRounds([]);
       }
     };
@@ -214,8 +219,8 @@ const SessionManagementCard = ({ styles: commonStyles }) => {
             </tr>
           </thead>
           <tbody>
-            {currentDisplayedRounds.length > 0 ? (
-              currentDisplayedRounds.map((round, index) => {
+            {(currentDisplayedRounds || []).length > 0 ? (
+              (currentDisplayedRounds || []).map((round, index) => {
                 const startTime = new Date(round.startAt);
                 const closeTime = new Date(round.closeAt);
 
diff --git a/frontend/src/components/attendancemanage/SessionManagementCard.module.css b/frontend/src/components/attendancemanage/SessionManagementCard.module.css
index 0780be4e..702149af 100644
--- a/frontend/src/components/attendancemanage/SessionManagementCard.module.css
+++ b/frontend/src/components/attendancemanage/SessionManagementCard.module.css
@@ -515,7 +515,6 @@
   width: 100%;
   min-width: 0;
   overflow-x: auto;
-  overflow-y: hidden;
   padding-bottom: 2px;
   margin-left: 0;
 }