Released in zsh 5.0.7 a security fix that disallow evaluation of the initial values of integer variables imported from the environment (they are instead treated as literal numbers). That could allow local privilege escalation, under some specific and atypical conditions where zsh is being invoked in privilege elevation contexts when the environment has not been properly sanitized, such as when zsh is invoked by sudo on systems where "env_reset" has been disabled.
Created zsh tracking bugs for this issue:
Affects: fedora-all [bug 1549288]
Don't allow environment variables 'OPTIND' and 'TRY_BLOCK_ERROR' to be inherited by shells called through zsh.
Mitigated by default on Red Hat Enterprise Linux versions 5, 6 and 7, since this is the default configuration on those versions.
Red Hat Product Security has rated this issue as having security impact of Low. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.