CVE-2026-99123 (GCVE-0-2026-99123)
Vulnerability from cvelistv5
Published
2026-10-28 10:34
Modified
2026-10-28 10:34
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: validate packet source for connected sockets virtio_transport_recv_pkt() looks up sockets first by the full source and destination tuple, then by destination only in the bound table. The fallback is needed for listening and connecting sockets, but sockets remain in the bound table after connect(), so it can also return a non-listening socket. The fallback does not validate the source address. In TCP_SYN_SENT, a RESPONSE from an unrelated source can transition the victim socket to TCP_ESTABLISHED while its stored remote address remains unchanged. Subsequent RW packets from that source are delivered through the same destination-only fallback. This was reproduced with capability-empty processes under different UIDs. The attacker discovered the target tuple through unprivileged AF_VSOCK sock_diag and caused the victim socket to read 16 attacker-chosen bytes; the intended peer-side socket read 0 of those 16 bytes. Add vsock_check_source() to validate the transport, source port and source CID against the peer stored in a non-listening socket. The local transport is the CID exception because its packets are generated internally with VMADDR_CID_LOCAL as their source, including connections using CID aliases. Use the helper after lock_sock() in the virtio receive path.
Impacted products
Vendor Product Version
Linux Linux Version: 06a8fc78367d070720af960dcecec917d3ae5f3b
Version: 06a8fc78367d070720af960dcecec917d3ae5f3b
Version: 06a8fc78367d070720af960dcecec917d3ae5f3b
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/af_vsock.h",
            "net/vmw_vsock/af_vsock.c",
            "net/vmw_vsock/virtio_transport_common.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6cd829de69efd9ed3a53aa2421004a0396eb2bd7",
              "status": "affected",
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "versionType": "git"
            },
            {
              "lessThan": "e9bf92de436ba55f33eaa55d7008e68551123cfd",
              "status": "affected",
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "versionType": "git"
            },
            {
              "lessThan": "dee44f41f206becb41c492899c1996cfd7f82a1b",
              "status": "affected",
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/af_vsock.h",
            "net/vmw_vsock/af_vsock.c",
            "net/vmw_vsock/virtio_transport_common.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.8"
            },
            {
              "lessThan": "4.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.59",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.59",
                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.13",
                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: validate packet source for connected sockets\n\nvirtio_transport_recv_pkt() looks up sockets first by the full source and\ndestination tuple, then by destination only in the bound table. The\nfallback is needed for listening and connecting sockets, but sockets remain\nin the bound table after connect(), so it can also return a non-listening\nsocket.\n\nThe fallback does not validate the source address. In TCP_SYN_SENT, a\nRESPONSE from an unrelated source can transition the victim socket to\nTCP_ESTABLISHED while its stored remote address remains unchanged.\nSubsequent RW packets from that source are delivered through the same\ndestination-only fallback.\n\nThis was reproduced with capability-empty processes under different UIDs.\nThe attacker discovered the target tuple through unprivileged AF_VSOCK\nsock_diag and caused the victim socket to read 16 attacker-chosen bytes;\nthe intended peer-side socket read 0 of those 16 bytes.\n\nAdd vsock_check_source() to validate the transport, source port and source\nCID against the peer stored in a non-listening socket. The local transport\nis the CID exception because its packets are generated internally with\nVMADDR_CID_LOCAL as their source, including connections using CID aliases.\n\nUse the helper after lock_sock() in the virtio receive path."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:38.600Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/6cd829de69efd9ed3a53aa2421004a0396eb2bd7"
        },
        {
          "url": "https://git.kernel.org/stable/c/e9bf92de436ba55f33eaa55d7008e68551123cfd"
        },
        {
          "url": "https://git.kernel.org/stable/c/dee44f41f206becb41c492899c1996cfd7f82a1b"
        }
      ],
      "title": "vsock/virtio: validate packet source for connected sockets",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99123",
    "datePublished": "2026-10-28T10:34:38.600Z",
    "dateReserved": "2026-09-25T10:25:14.393Z",
    "dateUpdated": "2026-10-28T10:34:38.600Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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