c-ares is an asynchronous resolver library. ares_inet_net_pton() is vulnerable to a buffer underflow for certain ipv6 addresses, in particular "0::00:00:00/2" was found to cause an issue. C-ares only uses this function internally for configuration purposes which would require an administrator to configure such an address via ares_set_sortlist(). However, users may externally use ares_inet_net_pton() for other purposes and thus be vulnerable to more severe issues. This issue has been fixed in 1.19.1.
https://www.debian.org/security/2023/dsa-5419
https://security.netapp.com/advisory/ntap-20240605-0005/
https://security.gentoo.org/glsa/202310-09
https://lists.debian.org/debian-lts-announce/2023/06/msg00034.html
https://github.com/c-ares/c-ares/security/advisories/GHSA-x6mf-cxr9-8q6v