Invalid access to memory - _SHA_Simple

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.11.2

Error message:
Invalid access to memory.

Stack trace:
(003E9B8F) System::SysFreeMem
(0089C9C2) C5067_3
(0089EA2A) ____ExceptionHandler
(0089B7E4) __ExceptionHandler
(0003EF0E) ntdll.dll
(0003F68A) ntdll.dll
(0088A3C7) _free
(0062DD13) _safefree
(0065B0AA) _SHA_Simple
(0064243B) _sshfwd_x11_is_local
(00719A64) TSecureShell::FreeBackend
(00714736) TSecureShell::Open
(00759E5F) TSFTPFileSystem::Open
(007981FF) TTerminal::Reopen
(0079A605) TTerminal::QueryReopen
(0079150D) TRobustOperationLoop::TryReopen
(0077E9FC) TSFTPFileSystem::SFTPSourceRobust
(0077DAB5) TSFTPFileSystem::CopyToRemote
(007AFAD1) TTerminal::CopyToRemote
(0000E312) TCustomScpExplorerForm::ExecuteFileOperation
(0000F11C) TCustomScpExplorerForm::ExecuteFileOperation
(0000F1A3) TCustomScpExplorerForm::ExecuteFileOperationCommand
(0000F32A) TCustomScpExplorerForm::ExecuteCopyOperationCommand
(000381EF) TNonVisualDataModule::ExplorerActionsExecute
(003BDDBC) System::Actions::TContainedActionList::ExecuteAction
(001A4EF5) Vcl::Actnlist::TCustomAction::Execute
(0037BC78) System::Classes::_18201
(00007E6F) USER32.DLL.CallNextHookEx
(000080CC) USER32.DLL
(0000966A) USER32.DLL
(000096DB) USER32.DLL.DispatchMessageW

(0089D02D) C5067_3
(0089E607) _ReThrowException
(00796AC1) TTerminal::Open
(007981FF) TTerminal::Reopen
(0079A605) TTerminal::QueryReopen
(0079150D) TRobustOperationLoop::TryReopen
(0077E9FC) TSFTPFileSystem::SFTPSourceRobust
(0077DAB5) TSFTPFileSystem::Copy

The problem happens rarely. I cannot reproduce it.