{"id":"CVE-2026-19577","revision":"7cc13f6287184b89bc6d9786aa20fae5","records":[{"revision":"7cc13f6287184b89bc6d9786aa20fae5","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-19577","aliases":[],"title":"Out-of-bounds read in IPv6 route forwarding when the nexthop neighbor has no link-layer address","description":"net_route_ipv6_packet() in subsys/net/ip/route_ipv6.c resolved the nexthop's link-layer address with net_nbr_get_lladdr(nbr->idx) without first checking whether the neighbor cache entry actually had a linked link-layer address. An unresolved neighbor carries idx == NET_NBR_LLADDR_UNKNOWN (0xff), and net_nbr_get_lladdr() in subsys/net/ip/nbr.c performs no runtime bounds check beyond a NET_ASSERT, returning &net_neighbor_lladdr[255] — roughly 2.5 KB past the end of an array whose default size is CONFIG_NET_IPV6_MAX_NEIGHBORS (8). Because the returned pointer is never NULL, the following lladdr == NULL guard does not catch it.\n\nThe function is reached from ipv6_route_packet() in subsys/net/ip/ipv6.c for every received unicast IPv6 packet whose destination is not a local address on the receiving interface; CONFIG_NET_IPV6_ROUTE is enabled by default whenever the IPv6 neighbor cache is, so no router or forwarding configuration is needed. net_route_ipv6_get_info() returns the packet's destination itself as the nexthop when a neighbor cache entry for it exists, and the cache lookup does not skip INCOMPLETE entries. An unauthenticated attacker on the same link can therefore force the unresolved state — for example by eliciting traffic to a spoofed, non-existent neighbor address so that net_ipv6_send_ns() creates an INCOMPLETE entry, or by sending a Router Advertisement with no source link-layer address option, which creates a persistently unresolved router neighbor — and then send a packet addressed to that neighbor.\n\nThe result is an out-of-bounds read at a fixed index past the neighbor link-layer address array. On builds with CONFIG_ASSERT enabled the assertion fires and the device panics, giving a repeatable remote denial of service. With assertions disabled, the stale out-of-bounds struct net_linkaddr drives a memcmp() over an attacker-uninfluenced length and, when its len byte passes the NET_LINK_ADDR_MAX_LENGTH check, up to 8 bytes of unrelated static RAM are copied into the outgoing frame's destination link-layer address and transmitted on the link, disclosing them to any listener. There is no out-of-bounds write and the offset is not attacker-controlled, which bounds the impact.","state":0,"publishedAt":"2026-10-11T17:14:55.032+00:00","modifiedAt":"2026-10-15T18:09:20.629+00:00","affected":[{"ecosystem":"https://github.com/zephyrproject-rtos/zephyr","name":"zephyr","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"zephyrproject\",\n                    \"product\": \"zephyr\",\n                    \"collectionURL\": \"https://github.com/zephyrproject-rtos/zephyr\",\n                    \"packageName\": \"zephyr\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"programFiles\": [\n                        \"subsys/net/ip/route.c\",\n                        \"subsys/net/ip/route_ipv6.c\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"net_route_ipv6_packet\"\n                        },\n                        {\n                            \"name\": \"net_route_packet\"\n                        }\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"1.8.0\",\n                            \"status\": \"affected\",\n                            \"lessThan\": \"4.5.0\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","score":7.1,"severity":"HIGH"}],"references":["https://github.com/zephyrproject-rtos/zephyr/commit/b0b0e8973d1967114adbb9ed1611d448b5a46519","https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-vv76-4m89-95q5"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-19577","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-19577","identifiers":["CVE-2026-19577"]},"retained":false,"historicalAffected":[]}],"coverage":[]}