stunnel4 segfault - error 4 in libssl.so.1.1

Package: stunnel4
Version: 3:5.44-1ubuntu3

Package: libssl1.1
Version: 1.1.1g-1+ubuntu18.04.1+deb.sury.org+1

stunnel4 is randomly crashing on ubuntu 18.04

Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc0a79d0 alloc=client.c:1398 free#1=ssl.c:117 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1b80d2ce0 alloc=../ssl/ssl_sess.c:180 free#1=../ssl/ssl_sess.c:765 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc020370 alloc=../crypto/asn1/tasn_new.c:122 free#1=ssl.c:117 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc13bcc0 alloc=../ssl/ssl_sess.c:180 free#1=../ssl/ssl_sess.c:765 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc046fe0 alloc=../crypto/stack/stack.c:64 free#1=../crypto/stack/stack.c:376 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1b821c4e0 alloc=../crypto/asn1/tasn_new.c:122 free#1=ssl.c:117 free#2=../crypto/asn1/tasn_fre.c:115
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc08d260 alloc=../ssl/statem/extensions.c:955 free#1=../ssl/ssl_sess.c:765 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc10e4c0 alloc=client.c:1398 free#1=ssl.c:117 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc0d9c40 alloc=client.c:1398 free#1=ssl.c:117 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc1f85a0 alloc=../crypto/lhash/lhash.c:109 free#1=../crypto/lhash/lhash.c:144 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc2284e0 alloc=client.c:1398 free#1=client.c:1410 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1b8095ea0 alloc=../ssl/ssl_sess.c:180 free#1=ssl.c:117 free#2=../ssl/ssl_sess.c:765
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1b8141240 alloc=../crypto/lhash/lhash.c:109 free#1=../crypto/lhash/lhash.c:144 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc1abf70 alloc=client.c:1398 free#1=ssl.c:117 free#2=ssl.c:117
Jul 19 19:37:47 localhost stunnel: LOG2[765]: Double free attempt: ptr=0x7fc1bc10e2c0 alloc=../crypto/lhash/lhash.c:109 free#1=../crypto/lhash/lhash.c:144 free#2=ssl.c:117
Jul 19 19:37:47 localhost kernel: [44649422.706497] stunnel4[21956]: segfault at 1e0 ip 00007fc1ca768b89 sp 00007fc1cabc99d8 error 4 in libssl.so.1.1[7fc1ca729000+81000]