A shell designed for interactive use, although it is also a powerful scripting language.
Multiple vulnerabilities have been discovered in Zsh. Please review the CVE identifiers referenced below for details.
A vulnerability in prompt expansion could be exploited through e.g. VCS_Info to execute arbitrary shell commands without a user's knowledge.
There is no known workaround at this time.
All Zsh users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-shells/zsh-5.8.1"