Please provide the steps to verify it.

The default buffer size is 128k (131072 bytes).

To verify create a CGI to accept the POST. I created one that simply echo's the data back and put it into /var/www/cgi-bin:

#!/usr/bin/perl

binmode(STDOUT);
binmode(STDIN);

print "Content-Type: text/plain\r\n";
print "\r\n";

while (<>) {
    print $_;
}

Modify nss.conf and set a specific cipher for cgi-bin which will cause a re-negotiation:

<Directory "/var/www/cgi-bin">
    NSSCipherSuite +rsa_3des_sha
    NSSOptions +ExportCertData +CompatEnvVars +StdEnvVars
</Directory>

Restart Apache

Generate a file that is within the default range:

$ tr -dc A-Za-z0-9 </dev/urandom | head -c 131072 > /tmp/data

Try to get the file:

$ wget -O - --no-check-certificate --post-file /tmp/data https://`hostname`:8443/cgi-bin/echo.pl

It should succeed.

Try a bigger file:

$ tr -dc A-Za-z0-9 </dev/urandom | head -c 131073 > /tmp/data

$ wget -O - --no-check-certificate --post-file /tmp/data https://`hostname`:8443/cgi-bin/echo.pl

It should fail with 413 Request Entity Too Large

Edit nss.conf again and set a new, larger buffer size to the cgi-bin Directory block:

NSSRenegBufferSize 1048576

Restart Apache

Try the same POST again:

$ wget -O - --no-check-certificate --post-file /tmp/data https://`hostname`:8443/cgi-bin/echo.pl

It should succeed

Verified using mod_nss ::
mod_nss-1.0.10-5.el6.x86_64

Steps followed to verify ::
https://bugzilla.redhat.com/show_bug.cgi?id=1214366#c10

Created attachment 1128150 [details]
console.log

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, 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://rhn.redhat.com/errata/RHBA-2016-0751.html