diff --git a/source/core/data/cia.c b/source/core/data/cia.c
index 8a1e311..0e4ede0 100644
--- a/source/core/data/cia.c
+++ b/source/core/data/cia.c
@@ -5,14 +5,25 @@
 #include "tmd.h"
 #include "../error.h"
 
-u64 cia_get_title_id(u8* cia) {
+Result cia_get_title_id(u64* titleId, u8* cia, size_t size) {
+    if(cia == NULL) {
+        return R_APP_INVALID_ARGUMENT;
+    }
+
+    if(size < 0x10) {
+        return R_APP_BAD_DATA;
+    }
+
     u32 headerSize = ((*(u32*) &cia[0x00]) + 0x3F) & ~0x3F;
     u32 certSize = ((*(u32*) &cia[0x08]) + 0x3F) & ~0x3F;
     u32 ticketSize = ((*(u32*) &cia[0x0C]) + 0x3F) & ~0x3F;
+    u32 offset = headerSize + certSize + ticketSize;
 
-    u8* tmd = &cia[headerSize + certSize + ticketSize];
+    if(offset >= size) {
+        return R_APP_BAD_DATA;
+    }
 
-    return tmd_get_title_id(tmd);
+    return tmd_get_title_id(titleId, &cia[offset], size - offset);
 }
 
 Result cia_file_get_smdh(SMDH* smdh, Handle handle) {
diff --git a/source/core/data/cia.h b/source/core/data/cia.h
index b1d08e4..f1831e4 100644
--- a/source/core/data/cia.h
+++ b/source/core/data/cia.h
@@ -2,5 +2,5 @@
 
 typedef struct SMDH_s SMDH;
 
-u64 cia_get_title_id(u8* cia);
+Result cia_get_title_id(u64* titleId, u8* cia, size_t size);
 Result cia_file_get_smdh(SMDH* smdh, Handle handle);
\ No newline at end of file
diff --git a/source/core/data/ticket.c b/source/core/data/ticket.c
index e538067..33a517e 100644
--- a/source/core/data/ticket.c
+++ b/source/core/data/ticket.c
@@ -1,9 +1,33 @@
 #include <3ds.h>
 
 #include "ticket.h"
+#include "../core.h"
 
-static u32 sigSizes[6] = {0x240, 0x140, 0x80, 0x240, 0x140, 0x80};
+#define NUM_SIG_TYPES 6
+static u32 sigSizes[NUM_SIG_TYPES] = {0x240, 0x140, 0x80, 0x240, 0x140, 0x80};
 
-u64 ticket_get_title_id(u8* ticket) {
-    return __builtin_bswap64(*(u64*) &ticket[sigSizes[ticket[0x03]] + 0x9C]);
+Result ticket_get_title_id(u64* titleId, u8* ticket, size_t size) {
+    if(ticket == NULL) {
+        return R_APP_INVALID_ARGUMENT;
+    }
+
+    if(size < 4) {
+        return R_APP_BAD_DATA;
+    }
+
+    u8 sigType = ticket[0x03];
+    if(sigType >= NUM_SIG_TYPES) {
+        return R_APP_BAD_DATA;
+    }
+
+    u32 offset = sigSizes[sigType] + 0x9C;
+    if(offset + sizeof(u64) > size) {
+        return R_APP_BAD_DATA;
+    }
+
+    if(titleId != NULL) {
+        *titleId = __builtin_bswap64(*(u64*) &ticket[offset]);
+    }
+
+    return 0;
 }
\ No newline at end of file
diff --git a/source/core/data/ticket.h b/source/core/data/ticket.h
index 3bea836..898b2b4 100644
--- a/source/core/data/ticket.h
+++ b/source/core/data/ticket.h
@@ -1,3 +1,3 @@
 #pragma once
 
-u64 ticket_get_title_id(u8* ticket);
\ No newline at end of file
+Result ticket_get_title_id(u64* titleId, u8* ticket, size_t size);
\ No newline at end of file
diff --git a/source/core/data/tmd.c b/source/core/data/tmd.c
index dd53ef5..2c25c2e 100644
--- a/source/core/data/tmd.c
+++ b/source/core/data/tmd.c
@@ -1,17 +1,89 @@
 #include <3ds.h>
 
 #include "tmd.h"
+#include "../core.h"
 
-static u32 sigSizes[6] = {0x240, 0x140, 0x80, 0x240, 0x140, 0x80};
+#define NUM_SIG_TYPES 6
+static u32 sigSizes[NUM_SIG_TYPES] = {0x240, 0x140, 0x80, 0x240, 0x140, 0x80};
 
-u64 tmd_get_title_id(u8* tmd) {
-    return __builtin_bswap64(*(u64*) &tmd[sigSizes[tmd[0x03]] + 0x4C]);
+static Result tmd_get(u8** out, u8* tmd, size_t tmdSize, u32 pos, size_t fieldSize) {
+    if(tmd == NULL) {
+        return R_APP_INVALID_ARGUMENT;
+    }
+
+    if(tmdSize < 4) {
+        return R_APP_BAD_DATA;
+    }
+
+    u8 sigType = tmd[0x03];
+    if(sigType >= NUM_SIG_TYPES) {
+        return R_APP_BAD_DATA;
+    }
+
+    u32 offset = sigSizes[sigType] + pos;
+    if(offset + fieldSize > tmdSize) {
+        return R_APP_BAD_DATA;
+    }
+
+    if(out != NULL) {
+        *out = &tmd[offset];
+    }
+
+    return 0;
 }
 
-u16 tmd_get_content_count(u8* tmd) {
-    return __builtin_bswap16(*(u16*) &tmd[sigSizes[tmd[0x03]] + 0x9E]);
+Result tmd_get_title_id(u64* titleId, u8* tmd, size_t size) {
+    u8* data = NULL;
+    Result res = tmd_get(&data, tmd, size, 0x4C, sizeof(u64));
+    if(R_FAILED(res)) {
+        return res;
+    }
+
+    if(titleId != NULL) {
+        *titleId = __builtin_bswap64(*(u64*) data);
+    }
+
+    return 0;
 }
 
-u8* tmd_get_content_chunk(u8* tmd, u32 index) {
-    return &tmd[sigSizes[tmd[0x03]] + 0x9C4 + (index * 0x30)];
+Result tmd_get_content_count(u16* contentCount, u8* tmd, size_t size) {
+    u8* data = NULL;
+    Result res = tmd_get(&data, tmd, size, 0x9E, sizeof(u16));
+    if(R_FAILED(res)) {
+        return res;
+    }
+
+    if(contentCount != NULL) {
+        *contentCount = __builtin_bswap16(*(u16*) data);
+    }
+
+    return 0;
+}
+
+Result tmd_get_content_id(u32* id, u8* tmd, size_t size, u32 num) {
+    u8* data = NULL;
+    Result res = tmd_get(&data, tmd, size, 0x9C4 + (num * 0x30), sizeof(u32));
+    if(R_FAILED(res)) {
+        return res;
+    }
+
+    if(id != NULL) {
+        *id = __builtin_bswap32(*(u32*) data);
+    }
+
+    return 0;
+}
+
+Result tmd_get_content_index(u16* index, u8* tmd, size_t size, u32 num) {
+    u8* data = NULL;
+    Result res = tmd_get(&data, tmd, size, 0x9C4 + (num * 0x30) + 0x4, sizeof(u16));
+    if(R_FAILED(res)) {
+        return res;
+    }
+
+    if(index != NULL) {
+        *index = __builtin_bswap16(*(u16*) data);
+    }
+
+    return 0;
 }
\ No newline at end of file
diff --git a/source/core/data/tmd.h b/source/core/data/tmd.h
index 43c143f..020e753 100644
--- a/source/core/data/tmd.h
+++ b/source/core/data/tmd.h
@@ -1,5 +1,6 @@
 #pragma once
 
-u64 tmd_get_title_id(u8* tmd);
-u16 tmd_get_content_count(u8* tmd);
-u8* tmd_get_content_chunk(u8* tmd, u32 index);
\ No newline at end of file
+Result tmd_get_title_id(u64* titleId, u8* tmd, size_t size);
+Result tmd_get_content_count(u16* contentCount, u8* tmd, size_t size);
+Result tmd_get_content_id(u32* id, u8* tmd, size_t size, u32 num);
+Result tmd_get_content_index(u16* index, u8* tmd, size_t size, u32 num);
\ No newline at end of file
diff --git a/source/fbi/action/installcdn.c b/source/fbi/action/installcdn.c
index 5c640a1..bb3f0d6 100644
--- a/source/fbi/action/installcdn.c
+++ b/source/fbi/action/installcdn.c
@@ -18,7 +18,7 @@ typedef struct {
     bool finishedPrompt;
 
     char tmdVersion[16];
-    u32 contentCount;
+    u16 contentCount;
     u16 contentIndices[CONTENTS_MAX];
     u32 contentIds[CONTENTS_MAX];
 
@@ -71,21 +71,28 @@ static Result action_install_cdn_open_dst(void* data, u32 index, void* initialRe
     install_cdn_data* installData = (install_cdn_data*) data;
 
     if(index == 0) {
-        installData->contentCount = tmd_get_content_count((u8*) initialReadBlock);
-        if(installData->contentCount > CONTENTS_MAX) {
-            return R_APP_OUT_OF_RANGE;
+        Result res = 0;
+
+        if(R_SUCCEEDED(res = tmd_get_content_count(&installData->contentCount, (u8*) initialReadBlock, installData->installInfo.bufferSize))) {
+            if(installData->contentCount <= CONTENTS_MAX) {
+                for(u32 i = 0; i < installData->contentCount; i++) {
+                    if(R_FAILED(res = tmd_get_content_id(&installData->contentIds[i], (u8*) initialReadBlock, installData->installInfo.bufferSize, i))
+                       || R_FAILED(res = tmd_get_content_index(&installData->contentIndices[i], (u8*) initialReadBlock, installData->installInfo.bufferSize, i))) {
+                        break;
+                    }
+                }
+
+                if(R_SUCCEEDED(res)) {
+                    installData->installInfo.total += installData->contentCount;
+
+                    res = AM_InstallTmdBegin(handle);
+                }
+            } else {
+                res = R_APP_OUT_OF_RANGE;
+            }
         }
 
-        for(u32 i = 0; i < installData->contentCount; i++) {
-            u8* contentChunk = tmd_get_content_chunk((u8*) initialReadBlock, i);
-
-            installData->contentIds[i] = __builtin_bswap32(*(u32*) &contentChunk[0x00]);
-            installData->contentIndices[i] = __builtin_bswap16(*(u16*) &contentChunk[0x04]);
-        }
-
-        installData->installInfo.total += installData->contentCount;
-
-        return AM_InstallTmdBegin(handle);
+        return res;
     } else {
         return AM_InstallContentBegin(handle, installData->contentIndices[index - 1]);
     }
diff --git a/source/fbi/action/installurl.c b/source/fbi/action/installurl.c
index b365407..91eb9ef 100644
--- a/source/fbi/action/installurl.c
+++ b/source/fbi/action/installurl.c
@@ -147,56 +147,58 @@ static Result action_install_url_open_dst(void* data, u32 index, void* initialRe
     if(*(u16*) initialReadBlock == 0x2020) {
         installData->contentType = CONTENT_CIA;
 
-        u64 titleId = cia_get_title_id((u8*) initialReadBlock);
+        u64 titleId = 0;
+        if(R_SUCCEEDED(res = cia_get_title_id(&titleId, (u8*) initialReadBlock, installData->installInfo.bufferSize))) {
+            FS_MediaType dest = fs_get_title_destination(titleId);
 
-        FS_MediaType dest = fs_get_title_destination(titleId);
+            bool n3ds = false;
+            if(R_SUCCEEDED(APT_CheckNew3DS(&n3ds)) && !n3ds && ((titleId >> 28) & 0xF) == 2) {
+                ui_view* view = prompt_display_yes_no("Confirmation", "Title is intended for New 3DS systems.\nContinue?", COLOR_TEXT, data, action_install_url_draw_top, action_install_url_n3ds_onresponse);
+                if(view != NULL) {
+                    svcWaitSynchronization(view->active, U64_MAX);
+                }
 
-        bool n3ds = false;
-        if(R_SUCCEEDED(APT_CheckNew3DS(&n3ds)) && !n3ds && ((titleId >> 28) & 0xF) == 2) {
-            ui_view* view = prompt_display_yes_no("Confirmation", "Title is intended for New 3DS systems.\nContinue?", COLOR_TEXT, data, action_install_url_draw_top, action_install_url_n3ds_onresponse);
-            if(view != NULL) {
-                svcWaitSynchronization(view->active, U64_MAX);
+                if(!installData->n3dsContinue) {
+                    return R_APP_SKIPPED;
+                }
             }
 
-            if(!installData->n3dsContinue) {
-                return R_APP_SKIPPED;
+            // Deleting FBI before it reinstalls itself causes issues.
+            u64 currTitleId = 0;
+            FS_MediaType currMediaType = MEDIATYPE_NAND;
+
+            if(envIsHomebrew() || R_FAILED(APT_GetAppletInfo((NS_APPID) envGetAptAppId(), &currTitleId, (u8*) &currMediaType, NULL, NULL, NULL)) || titleId != currTitleId || dest != currMediaType) {
+                AM_DeleteTitle(dest, titleId);
+                AM_DeleteTicket(titleId);
+
+                if(dest == MEDIATYPE_SD) {
+                    AM_QueryAvailableExternalTitleDatabase(NULL);
+                }
             }
-        }
 
-        // Deleting FBI before it reinstalls itself causes issues.
-        u64 currTitleId = 0;
-        FS_MediaType currMediaType = MEDIATYPE_NAND;
-
-        if(envIsHomebrew() || R_FAILED(APT_GetAppletInfo((NS_APPID) envGetAptAppId(), &currTitleId, (u8*) &currMediaType, NULL, NULL, NULL)) || titleId != currTitleId || dest != currMediaType) {
-            AM_DeleteTitle(dest, titleId);
-            AM_DeleteTicket(titleId);
-
-            if(dest == MEDIATYPE_SD) {
-                AM_QueryAvailableExternalTitleDatabase(NULL);
+            if(R_SUCCEEDED(res = AM_StartCiaInstall(dest, handle))) {
+                installData->currTitleId = titleId;
             }
         }
-
-        if(R_SUCCEEDED(res = AM_StartCiaInstall(dest, handle))) {
-            installData->currTitleId = titleId;
-        }
     } else if(*(u16*) initialReadBlock == 0x0100) {
-        installData->contentType = CONTENT_TICKET;
+        if(R_SUCCEEDED(res = ticket_get_title_id(&installData->ticketInfo.titleId, (u8*) initialReadBlock, installData->installInfo.bufferSize))) {
+            installData->contentType = CONTENT_TICKET;
 
-        if(!installData->cdnDecided) {
-            static const char* options[3] = {"Default\nVersion", "Select\nVersion", "No"};
-            static u32 optionButtons[3] = {KEY_A, KEY_X, KEY_B};
-            ui_view* view = prompt_display_multi_choice("Optional", "Install ticket titles from CDN?", COLOR_TEXT, options, optionButtons, 3, data, action_install_url_draw_top, action_install_url_cdn_check_onresponse);
-            if(view != NULL) {
-                svcWaitSynchronization(view->active, U64_MAX);
+            if(!installData->cdnDecided) {
+                static const char* options[3] = {"Default\nVersion", "Select\nVersion", "No"};
+                static u32 optionButtons[3] = {KEY_A, KEY_X, KEY_B};
+                ui_view* view = prompt_display_multi_choice("Optional", "Install ticket titles from CDN?", COLOR_TEXT, options, optionButtons, 3, data, action_install_url_draw_top, action_install_url_cdn_check_onresponse);
+                if(view != NULL) {
+                    svcWaitSynchronization(view->active, U64_MAX);
+                }
             }
+
+            installData->ticketInfo.inUse = false;
+            installData->ticketInfo.loaded = true;
+
+            AM_DeleteTicket(installData->ticketInfo.titleId);
+            res = AM_InstallTicketBegin(handle);
         }
-
-        installData->ticketInfo.titleId = ticket_get_title_id((u8*) initialReadBlock);
-        installData->ticketInfo.inUse = false;
-        installData->ticketInfo.loaded = true;
-
-        AM_DeleteTicket(installData->ticketInfo.titleId);
-        res = AM_InstallTicketBegin(handle);
     } else if(*(u32*) initialReadBlock == 0x58534433 /* 3DSX */ || *(u32*) initialReadBlock == 0x48444D53 /* SMDH */) {
         installData->contentType = CONTENT_3DSX_SMDH;