c-ares is a C library for asynchronous DNS requests. `ares__read_line()` is used to parse local configuration files such as `/etc/resolv.conf`, `/etc/nsswitch.conf`, the `HOSTALIASES` file, and if using a c-ares version prior to 1.27.0, the `/etc/hosts` file. If any of these configuration files has an embedded `NULL` character as the first character in a new line, it can lead to attempting to read memory prior to the start of the given buffer which may result in a crash. This issue is fixed in c-ares 1.27.0. No known workarounds exist. A vulnerability was found in c-ares where the ares__read_line() is used to parse local configuration files such as /etc/resolv.conf, /etc/nsswitch.conf, the HOSTALIASES file, and if using a c-ares version prior to 1.22.0, the /etc/hosts file. If the configuration files have an embedded NULL character as the first character in a new line, it can attempt to read memory before the start of the given buffer, which may result in a crash.
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