CVE-2026-99122 (GCVE-0-2026-99122)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:34 – Updated: 2026-10-31 12:43
VLAI
Title
vsock/vmci: validate packet source for connected sockets
Summary
In the Linux kernel, the following vulnerability has been resolved: vsock/vmci: validate packet source for connected sockets vmci_transport_recv_stream_cb() looks up sockets first by the full source and destination tuple, then by destination only in the bound table. The fallback can select a non-listening socket without checking whether the packet came from its stored peer. This was reproduced with two VMCI contexts. A RST from the context not stored in a TCP_SYN_SENT socket reset that socket after it was selected by the destination-only lookup. VMCI can process notification packets in bottom-half context when the socket is not owned by user context, or defer packets to a workqueue. Use vsock_check_source() after taking the socket lock in the bottom-half path, and recheck after lock_sock() in the workqueue path. Listening sockets continue to accept packets from any source. Reply with a RST addressed from the received packet before dropping a source that fails validation. This preserves the existing reset behavior for bound non-listening and concurrently closed sockets without directing the reset to a connected socket's stored peer.
Severity
7.3 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6653 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: d021c344051af91f42c5ba9fdedc176740cbd238 , < c027f8b429dbb2157fc1b503df196e272d947c89 (git)
Affected: d021c344051af91f42c5ba9fdedc176740cbd238 , < 90c423b62ec9be08177f74b07a47937ca8d2035b (git)
Affected: d021c344051af91f42c5ba9fdedc176740cbd238 , < ad9a7da3fa39c2d616ec0dd3cf6e30531d032fe7 (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.9
Unaffected: 0 , < 3.9 (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/vmw_vsock/vmci_transport.c"
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          "vendor": "Linux",
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              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/vmci: validate packet source for connected sockets\n\nvmci_transport_recv_stream_cb() looks up sockets first by the full source\nand destination tuple, then by destination only in the bound table. The\nfallback can select a non-listening socket without checking whether the\npacket came from its stored peer.\n\nThis was reproduced with two VMCI contexts. A RST from the context not\nstored in a TCP_SYN_SENT socket reset that socket after it was selected by\nthe destination-only lookup.\n\nVMCI can process notification packets in bottom-half context when the\nsocket is not owned by user context, or defer packets to a workqueue. Use\nvsock_check_source() after taking the socket lock in the bottom-half path,\nand recheck after lock_sock() in the workqueue path. Listening sockets\ncontinue to accept packets from any source.\n\nReply with a RST addressed from the received packet before dropping a\nsource that fails validation. This preserves the existing reset behavior\nfor bound non-listening and concurrently closed sockets without directing\nthe reset to a connected socket\u0027s stored peer."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.3,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - A local VMCI endpoint supplies the forged control datagram through IOCTL_VMCI_DATAGRAM_SEND, reaching vmci_datagram_dispatch() and the patched vmci_transport_recv_stream_cb(); vsock is therefore Local rather than a routable network vector.\nAC:L - vsock_diag_dump() exposes socket CIDs, ports, and state without an authorization check, after which a chosen RST deterministically misses vsock_find_connected_socket() and reaches the victim through vsock_find_bound_socket(); no race or uncontrolled condition is required.\nPR:L - vmci_host_open(), IOCTL_VMCI_INIT_CONTEXT, and IOCTL_VMCI_DATAGRAM_SEND contain no capability check, allowing a low-privilege VMX/local process with ordinary VMCI-device access to create an unrestricted context and submit the packet.\nUI:N - After the victim process has an ordinary bound connecting or established socket, the attacker\u0027s datagram alone drives vmci_transport_recv_pkt_work() and the reset handler; no victim user action is required.\nS:C - A packet owned by an attacker-controlled guest/VMX VMCI context is applied to a host-context socket by vmci_transport_recv_connecting_client() or vmci_transport_recv_connected(), crossing the VMCI virtualization or VMM-sandbox boundary.\nC:L - On an established socket, a forged WAITING_READ reaches vmci_transport_handle_waiting_read(), which conditionally returns WROTE to the foreign source based on vmci_qpair_produce_buf_ready(); this exposes limited queue-occupancy and traffic-state information, not payload bytes.\nI:N - The demonstrated RST and forged notification paths do not write application payloads, alter the intended VMCI queue pair, or corrupt memory; their changes to sk_state, peer_shutdown, and notification flags implement connection disruption rather than data modification.\nA:H - vmci_transport_recv_connecting_client() sets TCP_CLOSE and ECONNRESET, while vmci_transport_recv_connected() sets SOCK_DONE, SHUTDOWN_MASK, and TCP_CLOSING. Because tuples can be re-enumerated and RST injection repeated, the attacker can continuously terminate targeted VMCI client connections and fully deny their service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-31T12:43:23.512Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/c027f8b429dbb2157fc1b503df196e272d947c89"
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        },
        {
          "url": "https://git.kernel.org/stable/c/ad9a7da3fa39c2d616ec0dd3cf6e30531d032fe7"
        }
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      "title": "vsock/vmci: validate packet source for connected sockets",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99122",
    "datePublished": "2026-10-28T10:34:37.859Z",
    "dateReserved": "2026-09-25T10:25:14.393Z",
    "dateUpdated": "2026-10-31T12:43:23.512Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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      "date": "2026-11-08",
      "epss": "0.0012",
      "percentile": "0.01847"
    },
    "microsoft_vex": {
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      "cve": "CVE-2026-99122",
      "id": "msrc_CVE-2026-99122",
      "initial_release_date": "2026-10-29T01:04:18.000Z",
      "product_status:known_affected": "3",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "vsock/vmci: validate packet source for connected sockets",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-99122.json",
      "version": "3"
    },
    "nvd": {
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                "product": "Linux",
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/vmci: validate packet source for connected sockets\n\nvmci_transport_recv_stream_cb() looks up sockets first by the full source\nand destination tuple, then by destination only in the bound table. The\nfallback can select a non-listening socket without checking whether the\npacket came from its stored peer.\n\nThis was reproduced with two VMCI contexts. A RST from the context not\nstored in a TCP_SYN_SENT socket reset that socket after it was selected by\nthe destination-only lookup.\n\nVMCI can process notification packets in bottom-half context when the\nsocket is not owned by user context, or defer packets to a workqueue. Use\nvsock_check_source() after taking the socket lock in the bottom-half path,\nand recheck after lock_sock() in the workqueue path. Listening sockets\ncontinue to accept packets from any source.\n\nReply with a RST addressed from the received packet before dropping a\nsource that fails validation. This preserves the existing reset behavior\nfor bound non-listening and concurrently closed sockets without directing\nthe reset to a connected socket\u0027s stored peer."
          }
        ],
        "id": "CVE-2026-99122",
        "lastModified": "2026-10-31T13:17:56.467",
        "metrics": {
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                "attackVector": "LOCAL",
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                "baseScore": 7.3,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "LOW",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-11-06T03:25:56+00:00",
      "cve": "CVE-2026-99122",
      "id": "CVE-2026-99122",
      "initial_release_date": "2026-10-28T10:34:37.859000+00:00",
      "product_status:known_affected": "189",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: kernel: Denial of Service via unvalidated packet source in VMCI sockets",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99122.json",
      "version": "3"
    }
  }
}



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