{"id":"AZL-101975","summary":"CVE-2026-90138 affecting package kernel 6.6.150.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvsock: don't check the listener's sk_err in vsock_accept()\n\nSyzbot reported an issue which can be reproduced with these steps:\n\tr0 = socket(AF_VSOCK, SOCK_STREAM, 0)\n\tbind(r0, {VMADDR_CID_ANY, PORT})\n\tconnect(r0, {VMADDR_CID_LOCAL, PORT}) -\u003e -1, EPROTO (self-connect)\n\tlisten(r0, backlog)                   -\u003e 0\n\tr1 = socket(AF_VSOCK, SOCK_STREAM, 0)\n\tconnect(r1, {VMADDR_CID_LOCAL, PORT}) -\u003e 0\n\taccept(r0)                            -\u003e -1, EPROTO (stale sk_err)\n\nBasically, it creates a socket (r0) and triggers a self-connect after\nbinding it. This self-connect fails with EPROTO because it loops back\nto r0 while the socket is still in the TCP_SYN_SENT state, causing it\nto be incorrectly dispatched to the connecting-client path. The\nunexpected packet type encountered there sets sk_err to EPROTO.\n\nAfter that, it invokes a listen() call on the same socket. This\nlisten() call succeeds because the kernel's listening path never\ninspects or clears sk_err. Then, a new socket (r1) is created as a\nnormal client and connects to r0. However, vsock_accept() rejects this\nincoming connection because the listener's sk_err still holds the\nEPROTO error from the earlier failed self-connect.\n\nThis rejection causes the child socket created for r1's connection to\nnever be freed on virtio or hyperv transports; only the VMCI transport\nimplements pending_work to revisit and clean up a rejected socket.\n\nFor a non-blocking connect(), vsock_connect() may return -EINPROGRESS\nimmediately, and vsock_connect_timeout() can later set sk-\u003esk_err\nasynchronously.\n\nSince no vsock transport ever sets sk_err on a socket while it is in\nTCP_LISTEN state, checking it in vsock_accept() serves no purpose and\nonly carries forward errors left behind by earlier, unrelated\nconnection attempts on the same socket. Remove the checks so accept()\nno longer rejects valid incoming connections because of a stale\nerror, which also avoids the resource leak described above.","modified":"2026-09-18T14:15:21.938043370Z","published":"2026-09-17T17:17:06Z","upstream":["CVE-2026-90138"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90138"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-101975.json"}}],"schema_version":"1.9.0"}