DNS Stub Resolver Vulnerability in Zephyr Project

CVE-2026-79981

What is CVE-2026-79981?

The DNS stub resolver in the Zephyr Project has a vulnerability where it binds a single UDP socket per configured server with a fixed local port. This permits attackers, within the same network segment, to guess the transaction identifier and send forged DNS responses. An attacker can exploit this flaw to redirect applications by successfully competing against legitimate DNS servers. The issue can be mitigated by randomizing the source port with each query, increasing the difficulty of exploiting the vulnerability. This flaw poses risks primarily in environments where attackers can reach the device over UDP.

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