Merging the new haproxy won't solve the whole problem. There is a configuration per route (like an annotation) needed to configure the value None, Strict, or Lax (but Lax is the automatical default now, so that may be omitted). Otherwise the people would have to setup at least two haproxy routers for the different settings.

Target set to next release version while investigation is either
ongoing or pending. Will be considered for earlier release versions
when diagnosed and resolved.

A new openshift release is currently in progress and once that completes we can then push the changes for the newer haproxy-1.8.26 so that the RPM can be built and tagged. I expect that to occur today/tomorrow. 

Once that's in place we will resolve any CI issues in the associated change https://github.com/openshift/origin/pull/25542.

Verified with v3.11.318 and passed

# oc version
oc v3.11.318
kubernetes v1.11.0+d4cacc0
features: Basic-Auth GSSAPI Kerberos SPNEGO

Server https://hongli-311master-etcd-1:8443
openshift v3.11.318
kubernetes v1.11.0+d4cacc0

sh-4.2$ haproxy -v
HA-Proxy version 1.8.26 2020/08/03
Copyright 2000-2020 Willy Tarreau <willy>

sh-4.2$ rpm -qa | grep haproxy
haproxy18-1.8.26-1.el7.x86_64

# default SameSite=None
# curl https://edgeroute-hongli1.apps.1113-9m7.qe.rhcloud.com -v
<---snip--->
< Set-Cookie: a54306d9cf69be3311d72fb44eda92c6=0498e21abad7529161431eec7d46b162; path=/; HttpOnly; Secure; SameSite=None

# oc annotate route edgeroute router.openshift.io/cookie-same-site=Lax
# curl https://edgeroute-hongli1.apps.1113-9m7.qe.rhcloud.com -v
<---snip--->
< Set-Cookie: a54306d9cf69be3311d72fb44eda92c6=0498e21abad7529161431eec7d46b162; path=/; HttpOnly; Secure; SameSite=Lax

# oc annotate route edgeroute router.openshift.io/cookie-same-site=Strict --overwrite
# curl https://edgeroute-hongli1.apps.1113-9m7.qe.rhcloud.com -v
<---snip--->
< Set-Cookie: a54306d9cf69be3311d72fb44eda92c6=0498e21abad7529161431eec7d46b162; path=/; HttpOnly; Secure; SameSite=Strict

And a regression test is running now, will move this to Verified if no issue found during regression.

no issue found during the regression test, moving to VERIFIED.

Thanks @hongli !

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (OpenShift Container Platform 3.11.318 bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:5107