We will update RHEL 6.x to NSS 3.28, which is incompatible with Mozilla 50 and older versions, depending on which features are enabled in NSS RHEL.
Because we most like keep an older nss-softokn version in RHEL 6.x, this might be a non-issue.
However, I recommend that you pick up a small patch in Thunderbird, and other applications such as xulrunner (if we're using any such applications in RHEL), to prevent potentially issues.
The issue is not so much 3.28 as the X25519 that this version adds, and since the implementation of x25519 is in softokn, that is incompatibility with nss-softokn 3.28 package.
Red Hat Enterprise Linux 6 is in the Production 3 Phase. During the Production 3 Phase, Critical impact Security Advisories (RHSAs) and selected Urgent Priority Bug Fix Advisories (RHBAs) may be released as they become available.
The official life cycle policy can be reviewed here:
This issue does not meet the inclusion criteria for the Production 3 Phase and will be marked as CLOSED/WONTFIX. If this remains a critical requirement, please contact Red Hat Customer Support to request a re-evaluation of the issue, citing a clear business justification. Note that a strong business justification will be required for re-evaluation. Red Hat Customer Support can be contacted via the Red Hat Customer Portal at the following URL: