libmemcached-awesome is an open source C/C++ client library and tools for the memcached server. `libmemcached` could return data for a previously requested key, if that previous request timed out due to a low `POLL_TIMEOUT`. This issue has been addressed in version 1.1.4. Users are advised to upgrade. There are several ways to workaround or lower the probability of this bug affecting a given deployment. 1: use a reasonably high `POLL_TIMEOUT` setting, like the default. 2: use separate libmemcached connections for unrelated data. 3: do not re-use libmemcached connections in an unknown state.
https://github.com/php-memcached-dev/php-memcached/issues/531
https://github.com/awesomized/libmemcached/security/advisories/GHSA-wwmh-39wj-fx59
https://github.com/awesomized/libmemcached/releases/tag/1.1.4