{"id":"CVE-2026-99213","kind":"vulnerability","aliases":["CVE-2026-99213"],"related":[],"title":"Linux kernel vsock: connect and reset race can corrupt memory","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nvsock: treat TCP_CLOSING as once-established\n\nHandle the TCP_ESTABLISHED -> TCP_CLOSING transition on OP_RST, which can\nrace with the connect loop. Immediately break and return 0 on\nESTABLISHED/CLOSING. The return value of connect() should reflect what\nhappened up to the point the connection was established or failed. Events\nthat occur afterwards must not affect it. E.g. even if OP_RW has already\nset sk_err, connect() should still return 0, not ENOBUFS because of it.\nAdapt the inaccurate comment above signal_pending().\n\nResetting a socket that is still present in connected_table can lead to\nmemory corruption. The reporter noted lost transports for in-flight skbs,\nand I have reproduced crashes caused by re-insertion into connected_table.\n\n  list_add double add: new=, prev=, next=.\n  kernel BUG at lib/list_debug.c:35!\n  Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n  Workqueue: vsock-loopback vsock_loopback_work\n  RIP: 0010:__list_add_valid_or_report+0x11f/0x130\n  Call Trace:\n   vsock_insert_connected.cold+0xe/0x13\n   virtio_transport_recv_pkt+0x10e9/0x1460\n   vsock_loopback_work+0x305/0x480\n   process_one_work+0xe4c/0x1560\n   worker_thread+0x4f1/0xd60\n   kthread+0x36e/0x470\n   ret_from_fork+0x47b/0x6b0\n   ret_from_fork_asm+0x1a/0x30\n\nThis fix is supplementary to commit 002541ef650b (\"vsock: Ignore\nsignal/timeout on connect() if already established\"). Details under Link.","summary":"In the Linux kernel's vsock code, a reset arriving during connect can remove a socket that is still in the connected table, and a later re-insert can crash the kernel. The sources do not say what an attacker can do beyond the kernel crash and memory corruption.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["linux-kernel","other","virtualization","vsock"],"not_affected_if":["vsock-not-loaded"],"how_to_check":"- `uname -r` and compare against the kernel release that contains the fix, which the sources do not name\n- `lsmod | grep vsock` to see whether vsock modules are loaded at all","fix":"- Install the patched Linux kernel from your distribution once it ships the upstream fix (the referenced commit 002541ef650b is the supplementary context; the fixed version is unknown from the sources)","status":"open","published_at":"2026-10-28T11:17:42+00:00","first_seen_at":"2026-10-28T11:32:37+00:00","triaged_at":"2026-10-28T11:33:48+00:00","updated_at":"2026-10-28T11:33:48+00:00","category":"other","confidence":0.5,"triage":{"at":"2026-10-28T11:33:48Z","model":"claude-haiku-5-5","output":{"fix":"- Install the patched Linux kernel from your distribution once it ships the upstream fix (the referenced commit 002541ef650b is the supplementary context; the fixed version is unknown from the sources)","reach":"unknown","title":"Linux kernel vsock: connect and reset race can corrupt memory","impact":"medium","summary":"In the Linux kernel's vsock code, a reset arriving during connect can remove a socket that is still in the connected table, and a later re-insert can crash the kernel. The sources do not say what an attacker can do beyond the kernel crash and memory corruption.","category":"other","nicknames":[],"who_cares":["linux-kernel","vsock","virtualization"],"confidence":0.5,"needs_auth":"unknown","worst_case":"kernel crash and possible memory corruption on affected hosts","analyst_note":"Check the kernel.org stable commit or the NVD entry for the affected and fixed kernel versions and the exact trigger conditions.","how_to_check":"- `uname -r` and compare against the kernel release that contains the fix, which the sources do not name\n- `lsmod | grep vsock` to see whether vsock modules are loaded at all","needs_analyst":true,"not_affected_if":["vsock-not-loaded"],"who_is_affected":"Systems running a Linux kernel with vsock support (virtio-vsock or vsock loopback) that use it for connections between host and guests. Hosts without vsock loaded are unlikely to be exposed; the sources do not say which distributions or kernel ranges are affected.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000668,"input_tokens":3851,"output_tokens":565,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'+0':241C,246C,252C,257C,262C,266C,269C,274C,280C '-2026':12A,15A '-99213':13A,16A '0':112C,156C '0000':222C '0010':235C '002541ef650b':288C '1':223C '35':218C 'adapt':162C 'add':208C,210C,237C 'affect':140C 'afterward':137C 'alreadi':148C,295C 'arriv':32B 'asm':279C 'attack':63B 'beyond':66B 'break':109C 'bug':215C 'call':243C 'caus':199C 'close':86C,96C 'code':29B 'comment':165C 'commit':287C 'connect':4A,34B,44B,106C,119C,129C,152C,177C,205C,293C 'corrupt':9A,72B,183C 'crash':53B,69B,198C 'cve':11A,14A 'detail':297C 'doubl':209C 'e.g':142C 'enobuf':158C 'err':151C 'establish':90C,94C,131C,296C 'established/closing':114C 'even':143C 'event':134C 'fail':133C 'fix':283C 'flight':192C 'follow':78C 'fork':273C,278C 'handl':91C 'happen':123C 'ignor':290C 'immedi':108C 'in-flight':190C 'inaccur':164C 'insert':51B,203C 'invalid':220C 'kasan':225C 'kernel':2A,19B,26B,55B,68B,76C,214C 'kthread':268C 'later':48B 'lead':180C 'lib/list_debug.c':217C 'link':299C 'linux':1A,18B,25B,75C 'linux-kernel':17B 'list':207C,236C 'loop':107C 'loopback':230C,232C,255C 'lost':187C 'memori':10A,71B,182C 'must':138C 'new':211C 'next':213C 'nopti':226C 'note':186C 'occur':136C 'once-establish':88C 'one':260C 'oop':219C 'op':99C,145C 'opcod':221C 'pend':168C 'pkt':251C 'point':127C 'present':175C 'prev':212C 'process':259C 'race':7A,103C 're':50B,202C 're-insert':49B,201C 'recv':250C 'reflect':121C 'remov':36B 'report':185C,240C 'reproduc':197C 'reset':6A,31B,169C 'resolv':82C 'ret':271C,276C 'return':111C,116C,155C 'rip':234C 'rst':100C 'rw':146C 'say':60B 'set':149C 'signal':167C 'signal/timeout':291C 'sk':150C 'skbs':193C 'smp':224C 'socket':38B,171C 'sourc':57B 'still':41B,154C,174C 'supplementari':285C 'tabl':45B,178C,206C 'tcp':85C,93C,95C 'thread':265C 'trace':244C 'transit':97C 'transport':188C,249C 'treat':84C 'valid':238C 'valu':117C 'virtio':248C 'virtual':21B 'vsock':3A,22B,28B,83C,229C,231C,254C,289C 'vsock-loopback':228C 'vsock_insert_connected.cold':245C 'vulner':79C 'work':233C,256C,261C 'worker':264C 'workqueu':227C 'x10e9/0x1460':253C 'x11f/0x130':242C 'x1a/0x30':281C 'x305/0x480':258C 'x36e/0x470':270C 'x47b/0x6b0':275C 'x4f1/0xd60':267C 'xe/0x13':247C 'xe4c/0x1560':263C","nicknames":[],"mitigations":[],"who_affected":"Systems running a Linux kernel with vsock support (virtio-vsock or vsock loopback) that use it for connections between host and guests. Hosts without vsock loaded are unlikely to be exposed; the sources do not say which distributions or kernel ranges are affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-28T11:17:42+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99213","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99213","severity":null,"published_at":"2026-10-28T11:17:42+00:00","modified_at":"2026-10-28T11:17:42+00:00","first_seen_at":"2026-10-28T11:32:37+00:00","fetched_at":"2026-10-28T11:32:37+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"}