{"id":"CVE-2026-99057","kind":"vulnerability","aliases":["CVE-2026-99057"],"related":[],"title":"Linux kernel: Xen netfront leaks socket buffers when packet chains overflow","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nxen/netfront: don't leak the skb when xennet_fill_frags() fails\n\nWhen a response chain has more slots than fit in the skb's frags,\nxennet_fill_frags() returns an error and xennet_poll() jumps to its\nerror path.  That path moves what's left on tmpq to errq to be freed,\nbut the skb being filled was already dequeued from tmpq, so it's never\nfreed.  Each chain that overflows leaks the skb and the pages attached\nto it as frags, and the backend decides how many slots it sends.\n\nPut the skb back on tmpq before taking the error path, like the\nxennet_set_skb_gso() failure just above it does.","summary":"In the Linux kernel's Xen network frontend (netfront), a receive path that fails to fit a response chain into an skb leaks that skb and its attached pages. The backend controls how many slots it sends, so each overflowing chain leaks memory.","severity":"unknown","cvss":null,"epss":0.00209,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["infrastructure","linux-kernel","xen","xen-guests"],"not_affected_if":["kvm-or-bare-metal","non-xen-hosts"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-10-23T13:17:29+00:00","first_seen_at":"2026-10-23T21:57:33+00:00","triaged_at":"2026-10-25T04:53:58+00:00","updated_at":"2026-10-25T12:38:50+00:00","category":"infrastructure","confidence":0.5,"triage":{"at":"2026-10-25T04:53:58Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"unknown","title":"Linux kernel: Xen netfront leaks socket buffers when packet chains overflow","impact":"low","summary":"In the Linux kernel's Xen network frontend (netfront), a receive path that fails to fit a response chain into an skb leaks that skb and its attached pages. The backend controls how many slots it sends, so each overflowing chain leaks memory.","category":"infrastructure","nicknames":[],"who_cares":["linux-kernel","xen","xen-guests"],"confidence":0.5,"needs_auth":"unknown","worst_case":"Repeated overflowing packets exhaust guest memory, causing denial of service.","analyst_note":"Check the kernel.org stable commit and the NVD entry for affected kernel version ranges, fixed versions, and whether a remote backend can trigger it.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["non-xen-hosts","kvm-or-bare-metal"],"who_is_affected":"Linux guests running as Xen paravirtualized domains that use the netfront network driver are the systems to look at. The sources do not say which kernel versions are affected or whether the flaw is reachable from outside the host. Systems not running Linux on Xen, such as bare metal or KVM guests, are not affected.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000589,"input_tokens":3445,"output_tokens":490,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':13A,16A '-99057':14A,17A 'alreadi':137C 'attach':53B,156C 'back':173C 'backend':56B,163C 'buffer':7A 'chain':10A,44B,66B,93C,147C 'control':57B 'cve':12A,15A 'decid':164C 'dequeu':138C 'error':109C,116C,179C 'errq':127C 'fail':39B,89C 'failur':187C 'fill':87C,105C,135C 'fit':41B,98C 'follow':74C 'frag':88C,103C,106C,160C 'freed':130C,145C 'frontend':33B 'gso':186C 'guest':25B 'infrastructur':18B 'jump':113C 'kernel':2A,21B,29B,72C 'leak':5A,48B,67B,82C,150C 'left':123C 'like':181C 'linux':1A,20B,28B,71C 'linux-kernel':19B 'mani':59B,166C 'memori':68B 'move':120C 'netfront':4A,34B 'network':32B 'never':144C 'overflow':11A,65B,149C 'packet':9A 'page':54B,155C 'path':37B,117C,119C,180C 'poll':112C 'put':170C 'receiv':36B 'resolv':78C 'respons':43B,92C 'return':107C 'send':62B,169C 'set':184C 'skb':47B,50B,84C,101C,133C,152C,172C,185C 'slot':60B,96C,167C 'socket':6A 'take':177C 'tmpq':125C,140C,175C 'vulner':75C 'xen':3A,22B,24B,31B 'xen-guest':23B 'xen/netfront':79C 'xennet':86C,104C,111C,183C","nicknames":[],"mitigations":[],"who_affected":"Linux guests running as Xen paravirtualized domains that use the netfront network driver are the systems to look at. The sources do not say which kernel versions are affected or whether the flaw is reachable from outside the host. Systems not running Linux on Xen, such as bare metal or KVM guests, are not affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-23T13:17:29+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-99057","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99057","severity":null,"published_at":"2026-10-23T13:17:29+00:00","modified_at":"2026-10-23T13:17:29+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-2026-99057","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-99057","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"}