Denial of Service Vulnerability in Zephyr's DNS Resolver

CVE-2026-10657

What is CVE-2026-10657?

The vulnerability in Zephyr's DNS resolver arises from improper handling of mDNS (.local) queries. When the final label of the resolved hostname is shorter than the expected 7 bytes, the DNS resolver attempts to perform a comparison that reads past the end of the string. This buffer over-read can lead to a denial of service if it crosses an unmapped memory boundary. The issue particularly affects configurations where CONFIG_MDNS_RESOLVER is enabled and is present from version 1.10.0. The flaw can be mitigated by ensuring safer comparison handling to prevent reading beyond allocated memory.

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