About Apple security updates
For our customers' protection, Apple doesn't disclose, discuss, or confirm security issues until an investigation has occurred and patches or releases are available. Recent releases are listed on the Apple security updates page.
Apple security documents reference vulnerabilities by CVE-ID when possible.
Released February 19, 2018
Available for: iPhone 5s and later, iPad Air and later, and iPod touch 6th generation
Impact: Processing a maliciously crafted string may lead to heap corruption
Description: A memory corruption issue was addressed through improved input validation.
CVE-2018-4124: an anonymous researcher