diff --git a/thumbnail/thumbnail.h b/thumbnail/thumbnail.h
--- a/thumbnail/thumbnail.h
+++ b/thumbnail/thumbnail.h
@@ -69,6 +69,13 @@
      **/
     bool drawSubThumbnail(QPainter& p, const QString& filePath, int width, int height,
                           int xPos, int yPos, int frameWidth);
+
+    /**
+     *  Checks if path is on the same filesystem as thumbnail cache directory.
+     *  Returns true if so. False otherwise or if filesystem couldn't be checked.
+     */
+    bool sharesFilesystemWithThumbRoot(const QString &path);
+
 private:
     QString m_mimeType;
     int m_width;
@@ -83,6 +90,7 @@
     QSet<QString> m_propagationDirectories;
     QString m_thumbBasePath;
     qint64 m_maxFileSize;
+    dev_t m_thumbnailDirDeviceId = 0;
 };
 
 #endif
diff --git a/thumbnail/thumbnail.cpp b/thumbnail/thumbnail.cpp
--- a/thumbnail/thumbnail.cpp
+++ b/thumbnail/thumbnail.cpp
@@ -28,6 +28,7 @@
 #ifndef Q_OS_WIN
 #include <sys/ipc.h>
 #include <sys/shm.h>
+#include <sys/stat.h>
 #include <unistd.h> // nice()
 #endif
 
@@ -39,6 +40,7 @@
 #include <QCryptographicHash>
 #include <QImage>
 #include <QIcon>
+#include <QLoggingCategory>
 #include <QPainter>
 #include <QPixmap>
 #include <QUrl>
@@ -55,6 +57,10 @@
 #include <KMimeTypeTrader>
 #include <KServiceTypeTrader>
 #include <KPluginLoader>
+#include <Solid/Block>
+#include <Solid/Device>
+#include <Solid/StorageAccess>
+#include <Solid/StorageVolume>
 
 #include <kaboutdata.h>
 #include <kiconloader.h>
@@ -100,6 +106,8 @@
 //                    int depth
 //                Otherwise, the data returned is the image in PNG format.
 
+Q_LOGGING_CATEGORY(KIO_THUMBNAIL_LOG, "kio_thumbnail")
+
 using namespace KIO;
 //using namespace KCodecs;
 
@@ -550,8 +558,9 @@
             }
 
             dir.next();
+            QString canonicalFilePath = dir.fileInfo().canonicalFilePath();
 
-            if (validThumbnails > 0 && hadFirstThumbnail == dir.filePath()) {
+            if (validThumbnails > 0 && hadFirstThumbnail == canonicalFilePath) {
                 break; // Never show the same thumbnail twice
             }
 
@@ -561,7 +570,7 @@
                 continue;
             }
 
-            if (!drawSubThumbnail(p, dir.filePath(), segmentWidth, segmentHeight, xPos, yPos, frameWidth)) {
+            if (!drawSubThumbnail(p, canonicalFilePath, segmentWidth, segmentHeight, xPos, yPos, frameWidth)) {
                 continue;
             }
 
@@ -724,6 +733,20 @@
         if (!thumbnail.load(thumbPath.absoluteFilePath(thumbName))) {
             // no cached version is available, a new thumbnail must be created
 
+            // If file is on encrypted filesystem, we can't cache it unless it's on the same filesystem as thumbnail directory
+            bool allowCache;
+#ifdef _SYS_STAT_H
+            allowCache = sharesFilesystemWithThumbRoot(filePath);
+#else
+            allowCache = false;
+#endif
+            if (!allowCache) {
+                Solid::Device device = Solid::Device::storageAccessFromPath(filePath);
+                if (device.is<Solid::StorageVolume>()) {
+                    allowCache = device.as<Solid::StorageVolume>()->usage() != Solid::StorageVolume::UsageType::Encrypted;
+                }
+            }
+
             QSaveFile thumbnailfile(thumbPath.absoluteFilePath(thumbName));
             bool savedCorrectly = false;
             if (subCreator->create(filePath, cacheSize, cacheSize, thumbnail)) {
@@ -731,7 +754,7 @@
 
                 // The thumbnail has been created successfully. Store the thumbnail
                 // to the cache for future access.
-                if (thumbnailfile.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+                if (allowCache && thumbnailfile.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
                     savedCorrectly = thumbnail.save(&thumbnailfile, "PNG");
                 }
             } else {
@@ -748,6 +771,24 @@
     return true;
 }
 
+bool ThumbnailProtocol::sharesFilesystemWithThumbRoot(const QString& path)
+{
+    if (!m_thumbnailDirDeviceId) {
+        struct stat baseStat;
+        if (lstat(QFile::encodeName(m_thumbBasePath).data(), &baseStat) == -1) {
+            qCWarning(KIO_THUMBNAIL_LOG) << "Cannot read information about filesystem";
+            return false;
+        }
+        m_thumbnailDirDeviceId = baseStat.st_dev;
+    }
+    struct stat fileStat;
+    if(lstat(QFile::encodeName(path).data(), &fileStat) == -1) {
+        qCWarning(KIO_THUMBNAIL_LOG) << "Cannot read information about filesystem";
+        return false;
+    }
+    return m_thumbnailDirDeviceId == fileStat.st_dev;
+}
+
 void ThumbnailProtocol::scaleDownImage(QImage& img, int maxWidth, int maxHeight)
 {
     if (img.width() > maxWidth || img.height() > maxHeight) {