{"schemaVersion":3,"id":"CVE-2026-19673","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"ethernet_recv() in subsys/net/l2/ethernet/ethernet.c validates only that the first net_buf of a received frame holds a plain 14-byte struct net_eth_hdr. When the ethertype is 0x8100 and VLAN is enabled on the interface, the same buffer is reinterpreted as the 18-byte struct net_eth_vlan_hdr without re-checking the length: the VLAN TCI and the inner ethertype are read from offsets 14..17, past pkt->buffer->len, and hdr_len is raised to 18 so the subsequent net_buf_pull() removes more bytes than the buffer holds.\n\nA single unauthenticated frame of 14 to 17 bytes carrying the VLAN ethertype triggers this. No knowledge of the node's VLAN configuration is needed: net_eth_get_vlan_iface() returns the base interface for the priority tag 0, and a broadcast destination address satisfies the \"frame is for me\" test, so a 16-byte broadcast frame with ethertype 0x8100 and TCI 0x0000 reaches the pull. Nothing in the receive path enforces the 60-byte Ethernet minimum — the USB CDC ECM and CDC NCM gadget classes in particular hand host-supplied frames of any non-zero length straight to net_recv_data().\n\nWith assertions enabled, net_buf_simple_pull() asserts and the node panics. In a production build (assertions and CONFIG_NET_BUF_HARDENING off) the uint16_t buffer length underflows to 65534 and buf->data is advanced past the end of the fragment's storage, so every later parser reads far outside the buffer and any net_buf_add() on that fragment computes tailroom from the underflowed length. The result is a reliable remote denial of service and out-of-bounds access with information-disclosure and corruption potential.\n\nOnly configurations built with CONFIG_NET_VLAN=y that have a VLAN enabled on the receiving Ethernet interface, and whose MAC does not strip VLAN tags in hardware (ETHERNET_HW_VLAN_TAG_STRIP), are affected. The fix rejects the frame before the tag is read, so hdr_len is thereafter either 14 or 18 with both sizes validated against pkt->buffer->len.","dates":{"published":"2026-10-14T16:45:57.967Z","modified":"2026-10-16T15:31:46.383Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.1,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":7.1,"severity":"high","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":7.1,"severity":"high","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00339,"percentile":0.25851,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[{"date":"2026-10-15T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00339,"percentile":0.25851}],"last30":[{"date":"2026-10-15T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00339,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00339,"percentile":0.25851}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-125","name":"Out-of-bounds Read","description":"The product reads data past the end, or before the beginning, of the intended buffer.","type":"weakness","status":"Draft","abstraction":"Base","likelihoodOfExploit":null,"url":"https://cwe.mitre.org/data/definitions/125.html"}],"affected":[{"vendor":"zephyrproject","product":"zephyr","name":"zephyr","label":"zephyr","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 1.12.0, < 4.5.0","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 1.12.0, < 4.5.0","eol":null,"hubHref":"/vendor/zephyrproject/zephyr"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/fd3c6fedf6b639977a80e52b680b15672c31f3ef","label":"github.com/zephyrproject-rtos/zephyr/commit/fd3c6fedf6b639977a80e52b680b15672c31f3ef","hostname":"github.com","tags":["Patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-79rf-rwff-f4vg","label":"github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-79rf-rwff-f4vg","hostname":"github.com","tags":[]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-10-14T16:45:57.967Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-10-16T15:31:46.383Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":28,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T09:49:47.635Z","stale":false,"partial":false}}