glibc DNS resolver aborts on long search domains

The GNU C Library's DNS stub resolver can abort any process that looks up names if a search domain is long enough, the project has disclosed under CVE-2026-8674.

In glibc 2.26 through 2.44, loading resolver configuration from /etc/resolv.conf or the LOCALDOMAIN environment variable fails an internal consistency check when the search list contains a domain of roughly 200 characters or more. The library truncates the list into a fixed buffer, then asserts that the truncated copy still matches the full configuration. That check used the wrong size and mishandled a first entry that did not fit, so a correctly truncated list still tripped the assertion and killed the process.

Any program that resolves names through glibc is exposed, including long-running services that reload resolv.conf on the next query after it changes. Search domains are often written into that file from DHCP or VPN configuration, so an attacker on the local network may be able to trigger the crash without privileges on the target, depending on how the network stack validates those values.

The flaw was reported by Joshua Rogers. It is fixed in glibc 2.45. The advisory rates the issue CVSS 5.3 (adjacent network, high attack complexity, availability impact only).