CVE-2026-5856

Sažetak

Contiki-NG's DNS/mDNS resolver skip_name() in os/services/resolv/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata() invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attacker who sets nquestions higher than the number of complete questions present causes skip_name() to walk past the UDP packet buffer, and the returned pointer is cast to struct dns_answer * for further memory reads. On builds with RESOLV_CONF_SUPPORTS_MDNS enabled, any peer on the local segment can trigger the read unauthenticated via a multicast UDP 5353 packet with no outstanding query required; on standard DNS builds an attacker who can inject a UDP response from port 53 during an outstanding query can trigger the same read. Impact is out-of-bounds read of uip_buf and adjacent memory, disclosing memory contents or crashing the resolver.

Reference

CVSS

Base:	7.1
Impact:	4.2
Exploitability:	2.8

Pristup

Vektor	Složenost	Autentikacija
ADJACENT_NETWORK	LOW	NONE

Impact

Povjerljivost	Cjelovitost	Dostupnost
HIGH	NONE	LOW

CVSS vektor

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L

Zadnje važnije ažuriranje

07-08-2026 - 18:17

Objavljeno

06-08-2026 - 22:18