{"id":"CVE-2026-87042","summary":"Zephyr PTP: unvalidated Delay_Resp message interval lets an on-link peer wedge the PTP thread and flood the network","details":"The IEEE 1588 (PTP) port implementation in subsys/net/lib/ptp/port.c adopted the logMessageInterval field of a received Delay_Resp message without any validation. port_delay_resp_msg_process() stored the raw wire value (a full-range int8_t) into port_ds.log_min_delay_req_interval, and that value is later used as a shift count by port_timer_set_timeout() when the Delay_Req timer is armed. Values below about -30 truncate the computed timeout to zero, and values with a magnitude of 64 or more perform an undefined shift of a uint64_t; the standards-defined \"not applicable\" encoding 0x7F fell into the latter case as well.\n\nPTP messages are received over unauthenticated link-local traffic (UDP multicast on 224.0.1.129, IPv6 multicast, or raw IEEE 802.3), and the handler accepts a Delay_Resp from any sender as long as the port is a time receiver using the end-to-end delay mechanism and the message echoes the port identity and a pending sequence id — both of which the victim itself broadcasts in its Delay_Req. Any node on the same link can therefore inject a single crafted Delay_Resp, or simply become the time transmitter and advertise the bogus interval.\n\nOnce the delay timer is armed with a zero timeout, the cooperative PTP thread re-arms and retransmits a Delay_Req on every tick. Each transmission takes a buffer from the fixed CONFIG_PTP_MSG_POLL_SIZE message slab (default 10) and holds it on port-\u003edelay_req_list for three seconds, so the slab is emptied within milliseconds and ptp_msg_alloc() then blocks with K_FOREVER inside the only thread that frees those buffers — permanently stalling time synchronization until reboot. Where a transmit-timestamp callback on another thread keeps recycling buffers, the result is instead a sustained multicast Delay_Req flood and continuous CPU consumption. There is no memory corruption and no disclosure of data; the impact is availability of the PTP subsystem and of the local network segment.\n\nThe fix rejects intervals outside a representable range and treats 0x7F as \"not applicable\" as required by IEEE 1588-2019 Table 42. The equivalent unchecked adoption of logMessageInterval from Sync messages in port_sync_msg_process(), a weaker variant of the same issue, is fixed by the companion change 334bf57f416f (#118150), which applies the same range check, ignores the field for unicast Sync messages and treats 0x7F as not applicable.","aliases":["GHSA-cx9q-8hq3-7hpr"],"modified":"2026-11-11T13:22:01.782431713Z","published":"2026-11-10T22:07:40.237Z","database_specific":{"cwe_ids":["CWE-400"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/87xxx/CVE-2026-87042.json","cna_assigner":"zephyr"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/87xxx/CVE-2026-87042.json"},{"type":"PACKAGE","url":"https://github.com/zephyrproject-rtos/zephyr"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/334bf57f416f2f65745e68db98edf3615ec4e7ab"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/f6b9459f082ac8cc18b7d20a5c4ce1d86b7a55b5"},{"type":"ADVISORY","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-cx9q-8hq3-7hpr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-87042"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zephyrproject-rtos/zephyr","events":[{"introduced":"36940db938a8f4a1e919496793ed439850a221c2"},{"fixed":"28af05ca658cbacf745fd5b099566311c58ccb1d"},{"introduced":"684c9e8f32e4373a21098559f748f06915f950c9"},{"fixed":"41d10b59730406bbab4ca9f1fbbe9e96aafb4966"},{"fixed":"f6b9459f082ac8cc18b7d20a5c4ce1d86b7a55b5"},{"fixed":"334bf57f416f2f65745e68db98edf3615ec4e7ab"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"3.7.0"},{"fixed":"4.3.2"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"strategy":"StandardRange","range":[{"introduced":"4.4.0"},{"fixed":"4.5.0"}],"source":"AFFECTED_FIELD"},{"range":[{"fixed":"f6b9459f082ac8cc18b7d20a5c4ce1d86b7a55b5"}],"source":"REFERENCES_COMMIT"},{"source":"REFERENCES_COMMIT","range":[{"fixed":"334bf57f416f2f65745e68db98edf3615ec4e7ab"}]}]}}],"versions":["v4.3.1","v4.3.1-rc1","v4.4.0","v4.3.0","v4.3.0-rc3","v4.3.0-rc2","v4.3.0-rc1","v4.2.0","v4.2.0-rc3","v4.2.0-rc2","v4.2.0-rc1","v4.1.0","v4.1.0-rc3","v4.1.0-rc2","v4.1.0-rc1","v4.0.0","v4.0.0-rc3","v4.0.0-rc2","v4.0.0-rc1","v3.7.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-87042.json","vanir_signatures":[{"id":"CVE-2026-87042-7d602cd9","signature_type":"Line","signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/f6b9459f082ac8cc18b7d20a5c4ce1d86b7a55b5","target":{"file":"subsys/net/lib/ptp/port.c"},"deprecated":false,"digest":{"line_hashes":["94036799839478545832032624291967590025","191470327891161057917147613972139519019","153490886561403345424645645634336144214","262223992655772637080310719786240458273","335282868978118042377049586917948168027","56114059015642410194223020633694462263"],"threshold":0.9}},{"signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/f6b9459f082ac8cc18b7d20a5c4ce1d86b7a55b5","target":{"file":"subsys/net/lib/ptp/port.c","function":"port_delay_resp_msg_process"},"deprecated":false,"digest":{"function_hash":"140567501298484126317252360134747937271","length":1059},"id":"CVE-2026-87042-8cc24d49","signature_type":"Function"},{"signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/f6b9459f082ac8cc18b7d20a5c4ce1d86b7a55b5","target":{"file":"tests/net/ptp/port_events/src/main.c"},"deprecated":false,"digest":{"line_hashes":["115912546933217487597470634231500211550","148955078917707122786274470636792007992","95497352954979099598544632318331571201"],"threshold":0.9},"id":"CVE-2026-87042-db57cf26","signature_type":"Line"}],"vanir_signatures_modified":"2026-11-11T13:22:01Z"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}