zlib is a widely used free and patent unencumbered data compression library.
Tavis Ormandy of the Gentoo Linux Security Audit Team discovered a buffer overflow in zlib. A bounds checking operation failed to take invalid data into account, allowing a specifically malformed deflate data stream to overrun a buffer.
An attacker could construct a malformed data stream, embedding it within network communication or an application file format, potentially resulting in the execution of arbitrary code when decoded by the application using the zlib library.
There is no known workaround at this time.
All zlib users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=sys-libs/zlib-1.2.2-r1"