diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 6a8db43a..eda44d39 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -3673,6 +3673,7 @@ Helmut Binder <cco@aon.at>
  for fixing handling incomplete multi-packet CAT
  for fixing a memory leak in handling the NIT
  for reporting a possible memory leak in creating fonts
+ for fixing a possible deadlock in cDevice::DetachAllReceivers()
 
 Ulrich Eckhardt <uli@uli-eckhardt.de>
  for reporting a problem with shutdown after user inactivity in case a plugin is
diff --git a/HISTORY b/HISTORY
index bb560344..99158f26 100644
--- a/HISTORY
+++ b/HISTORY
@@ -9775,3 +9775,4 @@ Video Disk Recorder Revision History
 - Added some missing "AUTO" values to vdr.5 (thanks to Winfried Köhler).
 - Fixed handling zero bytes in cH264Parser (thanks to Christoph Haubrich).
 - Fixed handling error conditions in the index file (reported by Markus Ehrnsperger).
+- Fixed a possible deadlock in cDevice::DetachAllReceivers() (thanks to Helmut Binder).
diff --git a/device.c b/device.c
index fb251cd1..4b9c9cc7 100644
--- a/device.c
+++ b/device.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: device.c 5.4 2022/01/13 10:56:01 kls Exp $
+ * $Id: device.c 5.5 2022/01/24 16:53:45 kls Exp $
  */
 
 #include "device.h"
@@ -437,6 +437,12 @@ cDevice *cDevice::GetDeviceForTransponder(const cChannel *Channel, int Priority)
   return Device;
 }
 
+void cDevice::ReleaseCamSlot(void)
+{
+  if (camSlot && !camSlot->IsDecrypting() && !camSlot->IsActivating())
+     camSlot->Assign(NULL);
+}
+
 bool cDevice::HasCi(void)
 {
   return false;
@@ -1823,7 +1829,7 @@ bool cDevice::AttachReceiver(cReceiver *Receiver)
   return false;
 }
 
-void cDevice::Detach(cReceiver *Receiver)
+void cDevice::Detach(cReceiver *Receiver, bool ReleaseCam)
 {
   if (!Receiver || Receiver->device != this)
      return;
@@ -1845,8 +1851,8 @@ void cDevice::Detach(cReceiver *Receiver)
   if (camSlot) {
      if (Receiver->priority > MINPRIORITY) { // priority check to avoid an infinite loop with the CAM slot's caPidReceiver
         camSlot->StartDecrypting();
-        if (!camSlot->IsDecrypting() && !camSlot->IsActivating())
-           camSlot->Assign(NULL);
+        if (ReleaseCam)
+           ReleaseCamSlot();
         }
      }
   if (!receiversLeft)
@@ -1860,8 +1866,9 @@ void cDevice::DetachAll(int Pid)
      for (int i = 0; i < MAXRECEIVERS; i++) {
          cReceiver *Receiver = receiver[i];
          if (Receiver && Receiver->WantsPid(Pid))
-            Detach(Receiver);
+            Detach(Receiver, false);
          }
+     ReleaseCamSlot();
      }
 }
 
@@ -1869,7 +1876,8 @@ void cDevice::DetachAllReceivers(void)
 {
   cMutexLock MutexLock(&mutexReceiver);
   for (int i = 0; i < MAXRECEIVERS; i++)
-      Detach(receiver[i]);
+      Detach(receiver[i], false);
+  ReleaseCamSlot();
 }
 
 // --- cTSBuffer -------------------------------------------------------------
diff --git a/device.h b/device.h
index 63eef603..2d0ac12f 100644
--- a/device.h
+++ b/device.h
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: device.h 5.1 2021/05/21 12:51:16 kls Exp $
+ * $Id: device.h 5.2 2022/01/24 16:53:45 kls Exp $
  */
 
 #ifndef __DEVICE_H
@@ -465,6 +465,8 @@ public:
 
 private:
   cCamSlot *camSlot;
+  void ReleaseCamSlot(void);
+         ///< Releases the CAM slot if it is currently not used.
 public:
   virtual bool HasCi(void);
          ///< Returns true if this device has a Common Interface.
@@ -852,8 +854,11 @@ public:
        ///< Returns true if we are currently receiving. The parameter has no meaning (for backwards compatibility only).
   bool AttachReceiver(cReceiver *Receiver);
        ///< Attaches the given receiver to this device.
-  void Detach(cReceiver *Receiver);
+  void Detach(cReceiver *Receiver, bool ReleaseCam = true);
        ///< Detaches the given receiver from this device.
+       ///< If ReleaseCam is true, the CAM slot will be released if it
+       ///< is no longer used. Otherwise the caller must call ReleaseCamSlot() after
+       ///< calling this function.
   void DetachAll(int Pid);
        ///< Detaches all receivers from this device for this pid.
   virtual void DetachAllReceivers(void);