CVE-2026-8674 Assertion failure in the DNS stub resolver with a long search domain

What is CVE-2026-8674?

CVE-2026-8674 is a medium-severity denial of service vulnerability in The GNU C Library glibc, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Initializing the DNS stub resolver from an /etc/resolv.conf file, or a LOCALDOMAIN environment variable, whose search list contains a domain of roughly 200 characters or more in the GNU C Library version 2.26 to 2.44 results in an assertion failure which aborts the process.

The resolver truncates the search list when copying it into the fixed-size _res.defdname buffer, then asserts that the copy is consistent with the full configuration. The consistency check compared against the wrong size and did not handle a first entry that does not fit, so a correctly truncated list failed the assertion. Any process that resolves names through the library is affected, including long-running processes that reload /etc/resolv.conf on the next query after it changes. Search domains are commonly written to /etc/resolv.conf from data received over DHCP or from a VPN server, so an attacker on the local network may be able to trigger this without privileges on the target system, subject to validation by the network configuration software.

Weakness: CWE-617

Which versions are affected by CVE-2026-8674?

How do I fix CVE-2026-8674?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-8674 being exploited?

There is no known exploitation of CVE-2026-8674 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-101843, BELL-CVE-2026-8674, DEBIAN-CVE-2026-8674, ECHO-00de-f7d3-2e21, GHSA-qghr-qhfc-4hxp, OESA-2026-4016 and 2 more.