{"id":"CVE-2026-45840","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: cap upcall PID array size and pre-size vport replies\n\nThe vport netlink reply helpers allocate a fixed-size skb with\nnlmsg_new(NLMSG_DEFAULT_SIZE, ...) but…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: cap upcall PID array size and pre-size vport replies\n\nThe vport netlink reply helpers allocate a fixed-size skb with\nnlmsg_new(NLMSG_DEFAULT_SIZE, ...) but…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.17, < 5.10.258","linux_kernel >= 5.11, < 5.15.209","linux_kernel >= 5.16, < 6.1.175","linux_kernel >= 6.2, < 6.6.141","linux_kernel >= 6.7, < 6.12.91","linux_kernel >= 6.13, < 6.18.33","linux_kernel >= 6.19, < 7.0.10"],"patched":["linux_kernel 7.0.10"],"published":"2026-05-27","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:19:36.710","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-45840","references":[{"url":"https://git.kernel.org/stable/c/1d6c02b86329883aa467a3a61f8d34369db73a2f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2091c6aa0df6aba47deb5c8ab232b1cb60af3519","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8d59b80e69dddb665eb2de36e62859ab2073470e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b39f763d720d623218bc1d95ace6855d7b474e81","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d9e47e29aacb9f8a9d59feb6ab5b128a9bbb40b0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f99ac36b5d7c719d08a69fcdecce40f78a874e15","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f9ef3db77a383d66847fd082c2b437d8ae4d9c63","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fa6e90bc443bed8dc0d55bc5ea5b27ffdfe37704","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00162,"epssPercentile":0.05069,"ingestedAt":"2026-10-15T03:30:12.878Z","slug":"CVE-2026-45840","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: cap upcall PID array size and pre-size vport replies\n\nThe vport netlink reply helpers allocate a fixed-size skb with\nnlmsg_new(NLMSG_DEFAULT_SIZE, ...) but serialize the full upcall PID\narray via ovs_vport_get_upcall_portids().  Since\novs_vport_set_upcall_portids() accepts any non-zero multiple of\nsizeof(u32) with no upper bound, a CAP_NET_ADMIN user can install a PID\narray large enough to overflow the reply buffer, causing nla_put() to\nfail with -EMSGSIZE and hitting BUG_ON(err < 0).  On systems with\nunprivileged user namespaces enabled (e.g., Ubuntu default), this is\nreachable via unshare -Urn since OVS vport mutation operations use\nGENL_UNS_ADMIN_PERM.\n\n kernel BUG at net/openvswitch/datapath.c:2414!\n Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n CPU: 1 UID: 0 PID: 65 Comm: poc Not tainted 7.0.0-rc7-00195-geb216e422044 #1\n RIP: 0010:ovs_vport_cmd_set+0x34c/0x400\n Call Trace:\n  <TASK>\n  genl_family_rcv_msg_doit (net/netlink/genetlink.c:1116)\n  genl_rcv_msg (net/netlink/genetlink.c:1194)\n  netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n  genl_rcv (net/netlink/genetlink.c:1219)\n  netlink_unicast (net/netlink/af_netlink.c:1344)\n  netlink_sendmsg (net/netlink/af_netlink.c:1894)\n  __sys_sendto (net/socket.c:2206)\n  __x64_sys_sendto (net/socket.c:2209)\n  do_syscall_64 (arch/x86/entry/syscall_64.c:63)\n  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n  </TASK>\n Kernel panic - not syncing: Fatal exception\n\nReject attempts to set more PIDs than nr_cpu_ids in\novs_vport_set_upcall_portids(), and pre-compute the worst-case reply\nsize in ovs_vport_cmd_msg_size() based on that bound, similar to the\nexisting ovs_dp_cmd_msg_size().  nr_cpu_ids matches the cap already\nused by the per-CPU dispatch configuration on the datapath side\n(ovs_dp_cmd_fill_info() serialises at most nr_cpu_ids PIDs), so the\ntwo sides stay consistent.\n\n## Affected\n\n- `linux_kernel >= 3.17, < 5.10.258`\n- `linux_kernel >= 5.11, < 5.15.209`\n- `linux_kernel >= 5.16, < 6.1.175`\n- `linux_kernel >= 6.2, < 6.6.141`\n- `linux_kernel >= 6.7, < 6.12.91`\n- `linux_kernel >= 6.13, < 6.18.33`\n- `linux_kernel >= 6.19, < 7.0.10`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.10`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}