{"id":"CVE-2026-98906","kind":"vulnerability","aliases":["CVE-2026-98906"],"related":[],"title":"Linux kernel: failed lan966x MTU change leaves RX state inconsistent","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lan966x: restore RX state on reload failure\n\nlan966x_fdma_reload() backs up rx->page_pool and rx->fdma before\nreallocating the RX resources for the new MTU. If the allocation fails,\nthe restore path puts these fields back before restarting RX.\n\nHowever, the reload path also updates rx->page_order and rx->max_mtu\nbefore calling lan966x_fdma_rx_alloc(). These fields are not restored on\nfailure, so RX can be restarted with the old pages, old FDMA state and\nold page pool, but with the page geometry from the failed new MTU.\n\nThis can make the XDP path advertise a frame size derived from the new\npage_order while the actual RX pages still come from the old allocation.\nFor example, after a failed reload to a jumbo MTU, xdp_init_buff() may be\ncalled with a frame size larger than the restored RX pages.\n\nlan966x_fdma_rx_alloc_page_pool() also registers the newly allocated page\npool with each port's XDP RXQ before fdma_alloc_coherent() is called. If\nfdma_alloc_coherent() fails, the new page pool is destroyed, but the\nrollback path does not restore the per-port XDP RXQ mem model\nregistration either.\n\nSave and restore rx->page_order and rx->max_mtu, and restore the old page\npool registration for each port's XDP RXQ before RX is started again.\nThis keeps the restored RX state consistent after a failed reload.","summary":"When a Microchip lan966x network driver reload to a new MTU fails, the restore path keeps the new page geometry and XDP queue registration while reusing old RX pages. The sources do not describe an attacker-controlled exploit path, only a driver state inconsistency that can make the XDP path use a frame size larger than the restored pages.","severity":"unknown","cvss":null,"epss":0.00206,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["embedded","lan966x","linux-kernel","networking","package"],"not_affected_if":["no-lan966x-hardware"],"how_to_check":"- unknown","fix":"- Update to a Linux kernel release that includes the upstream commit 'net: lan966x: restore RX state on reload failure' (version unknown from the sources)","status":"open","published_at":"2026-10-23T12:18:24+00:00","first_seen_at":"2026-10-23T21:57:33+00:00","triaged_at":"2026-10-25T04:58:34+00:00","updated_at":"2026-10-25T12:38:50+00:00","category":"package","confidence":0.5,"triage":{"at":"2026-10-25T04:58:34Z","model":"claude-haiku-5-5","output":{"fix":"- Update to a Linux kernel release that includes the upstream commit 'net: lan966x: restore RX state on reload failure' (version unknown from the sources)","reach":"local","title":"Linux kernel: failed lan966x MTU change leaves RX state inconsistent","impact":"low","summary":"When a Microchip lan966x network driver reload to a new MTU fails, the restore path keeps the new page geometry and XDP queue registration while reusing old RX pages. The sources do not describe an attacker-controlled exploit path, only a driver state inconsistency that can make the XDP path use a frame size larger than the restored pages.","category":"package","nicknames":[],"who_cares":["linux-kernel","lan966x","embedded","networking"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown; driver state inconsistency after a failed MTU change","analyst_note":"Check the NVD entry and the upstream kernel commit for affected and fixed kernel versions and any exploitability detail.","how_to_check":"- unknown","needs_analyst":true,"not_affected_if":["no-lan966x-hardware"],"who_is_affected":"Systems running the Linux kernel with the lan966x Ethernet driver (Microchip LAN966x SoC), where MTU changes can be triggered and XDP is in use. Systems without this hardware or driver can skip it. The sources do not say which kernel versions are affected.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"low"},"cost_usd":0.000633,"input_tokens":3710,"output_tokens":525,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':12A,15A '-98906':13A,16A 'actual':206C 'advertis':194C 'alloc':124C,154C,214C,244C,251C,262C,268C 'also':140C,247C 'attack':60B 'attacker-control':59B 'back':105C,132C 'buff':227C 'call':150C,230C,265C 'chang':6A 'coher':263C,269C 'come':210C 'consist':328C 'control':61B 'cve':11A,14A 'deriv':198C 'describ':57B 'destroy':276C 'driver':29B,66B 'either':293C 'embed':17B 'exampl':216C 'exploit':62B 'fail':3A,35B,125C,185C,219C,270C,331C 'failur':101C,161C 'fdma':103C,112C,152C,172C,242C,261C,267C 'field':131C,156C 'follow':89C 'frame':77B,196C,233C 'geometri':43B,182C 'howev':136C 'inconsist':10A,68B 'init':226C 'jumbo':223C 'keep':39B,323C 'kernel':2A,21B,87C 'lan966x':4A,18B,27B,95C,102C,151C,241C 'larger':79B,235C 'leav':7A 'linux':1A,20B,86C 'linux-kernel':19B 'make':71B,190C 'max':147C,302C 'may':228C 'mem':290C 'microchip':26B 'model':291C 'mtu':5A,34B,121C,148C,187C,224C,303C 'net':94C 'network':22B,28B 'new':33B,41B,120C,186C,201C,272C 'newli':250C 'old':50B,169C,171C,175C,213C,307C 'order':144C,203C,299C 'packag':23B 'page':42B,52B,83B,108C,143C,170C,176C,181C,202C,208C,240C,245C,252C,273C,298C,308C 'path':38B,63B,74B,128C,139C,193C,280C 'per':286C 'per-port':285C 'pool':109C,177C,246C,253C,274C,309C 'port':256C,287C,313C 'put':129C 'queue':46B 'realloc':114C 'regist':248C 'registr':47B,292C,310C 'reload':30B,100C,104C,138C,220C,332C 'resolv':93C 'resourc':117C 'restart':134C,166C 'restor':37B,82B,96C,127C,159C,238C,283C,296C,305C,325C 'reus':49B 'rollback':279C 'rx':8A,51B,97C,107C,111C,116C,135C,142C,146C,153C,163C,207C,239C,243C,297C,301C,318C,326C 'rxq':259C,289C,316C 'save':294C 'size':78B,197C,234C 'sourc':54B 'start':320C 'state':9A,67B,98C,173C,327C 'still':209C 'updat':141C 'use':75B 'vulner':90C 'xdp':45B,73B,192C,225C,258C,288C,315C","nicknames":[],"mitigations":[],"who_affected":"Systems running the Linux kernel with the lan966x Ethernet driver (Microchip LAN966x SoC), where MTU changes can be triggered and XDP is in use. Systems without this hardware or driver can skip it. The sources do not say which kernel versions are affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-23T12:18:24+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-98906","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98906","severity":null,"published_at":"2026-10-23T12:18:24+00:00","modified_at":"2026-10-23T12:18:24+00:00","first_seen_at":"2026-10-23T21:57:33+00:00","fetched_at":"2026-10-23T22:29:03+00:00","note":null},{"source":"epss","external_id":"CVE-2026-98906","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98906","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-25T12:38:50+00:00","fetched_at":"2026-10-25T12:38:50+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}