{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2026-23086",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-23086",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-02-04T16:08:10.047Z",
    "updatedAt": "2026-10-19T18:25:30.062Z",
    "importedAt": "2026-10-24T01:58:02.025Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "vsock/virtio: cap TX credit to local buffer size",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/virtio: cap TX credit to local buffer size\n\nThe virtio transports derives its TX credit directly from peer_buf_alloc,\nwhich is set from the remote endpoint's SO_VM_SOCKETS_BUFFER_SIZE value.\n\nOn the host side this means that the amount of data we are willing to\nqueue for a connection is scaled by a guest-chosen buffer size, rather\nthan the host's own vsock configuration. A malicious guest can advertise\na large buffer and read slowly, causing the host to allocate a\ncorrespondingly large amount of sk_buff memory.\nThe same thing would happen in the guest with a malicious host, since\nvirtio transports share the same code base.\n\nIntroduce a small helper, virtio_transport_tx_buf_size(), that\nreturns min(peer_buf_alloc, buf_alloc), and use it wherever we consume\npeer_buf_alloc.\n\nThis ensures the effective TX window is bounded by both the peer's\nadvertised buffer and our own buf_alloc (already clamped to\nbuffer_max_size via SO_VM_SOCKETS_BUFFER_MAX_SIZE), so a remote peer\ncannot force the other to queue more data than allowed by its own\nvsock settings.\n\nOn an unpatched Ubuntu 22.04 host (~64 GiB RAM), running a PoC with\n32 guest vsock connections advertising 2 GiB each and reading slowly\ndrove Slab/SUnreclaim from ~0.5 GiB to ~57 GiB; the system only\nrecovered after killing the QEMU process. That said, if QEMU memory is\nlimited with cgroups, the maximum memory used will be limited.\n\nWith this patch applied:\n\n  Before:\n    MemFree:        ~61.6 GiB\n    Slab:           ~142 MiB\n    SUnreclaim:     ~117 MiB\n\n  After 32 high-credit connections:\n    MemFree:        ~61.5 GiB\n    Slab:           ~178 MiB\n    SUnreclaim:     ~152 MiB\n\nOnly ~35 MiB increase in Slab/SUnreclaim, no host OOM, and the guest\nremains responsive.\n\nCompatibility with non-virtio transports:\n\n  - VMCI uses the AF_VSOCK buffer knobs to size its queue pairs per\n    socket based on the local vsk->buffer_* values; the remote side\n    cannot enlarge those queues beyond what the local endpoint\n    configured.\n\n  - Hyper-V's vsock transport uses fixed-size VMBus ring buffers and\n    an MTU bound; there is no peer-controlled credit field comparable\n    to peer_buf_alloc, and the remote endpoint cannot drive in-flight\n    kernel memory above those ring sizes.\n\n  - The loopback path reuses virtio_transport_common.c, so it\n    naturally follows the same semantics as the virtio transport.\n\nThis change is limited to virtio_transport_common.c and thus affects\nvirtio-vsock, vhost-vsock, and loopback, bringing them in line with the\n\"remote window intersected with local policy\" behaviour that VMCI and\nHyper-V already effectively have.\n\n[Stefano: small adjustments after changing the previous patch]\n[Stefano: tweak the commit message]",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "fef7110ae5617555c792a2bb4d27878d84583adf"
            },
            {
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "d9d5f222558b42f6277eafaaa6080966faf37676"
            },
            {
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "c0e42fb0e054c2b2ec4ee80f48ccd256ae0227ce"
            },
            {
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "84ef86aa7120449828d1e0ce438c499014839711"
            },
            {
              "version": "06a8fc78367d070720af960dcecec917d3ae5f3b",
              "status": "affected",
              "versionType": "git",
              "lessThan": "8ee784fdf006cbe8739cfa093f54d326cbf54037"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "4.8",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "4.8"
            },
            {
              "version": "6.1.162",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "version": "6.6.122",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "version": "6.12.68",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.18.8",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "version": "6.19",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}