{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/xen/pvcalls-front.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "d1297a9e2fd6ce08678b370d41bc980ca798f809",
              "status": "affected",
              "version": "2195046bfd69e487d9a76dc47840f15c8412840c",
              "versionType": "git"
            },
            {
              "lessThan": "d33846c8dcc06b83b7acdeac1e8bfbb5c0c26cb2",
              "status": "affected",
              "version": "2195046bfd69e487d9a76dc47840f15c8412840c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/xen/pvcalls-front.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.15"
            },
            {
              "lessThan": "4.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxen/pvcalls: bound backend response req_id before indexing rsp[]\n\npvcalls_front_event_handler() takes req_id directly from the\nbackend-supplied ring response and uses it to index the fixed-size\nbedata-\u003ersp[] array for a memcpy() and a store, with no range check. A\nmalicious or buggy backend can set req_id past PVCALLS_NR_RSP_PER_RING\nand drive an out-of-bounds write past the bedata allocation.\n\nreq_id was also declared int while the wire field rsp-\u003ereq_id is u32, so\na range check on the signed value alone is insufficient: a backend\nreq_id of 0xffffffff becomes -1, passes a \u003e= PVCALLS_NR_RSP_PER_RING\ntest and indexes bedata-\u003ersp[-1]. Declare req_id as u32 so a single\nbound covers both ends.\n\nA backend that sends an out-of-range req_id has violated the wire\nprotocol, so rather than silently dropping the response, log once and\nstop trusting the backend: set bedata-\u003edisabled. The event handler then\nignores further responses, and the request paths that wait for a\nresponse return -EIO instead of blocking forever. This mirrors the\nfatal-error handling xen-netback uses (xenvif_fatal_tx_err()).\n\nThe pvcalls frontend currently trusts its backend, so this is not a\nclassic-Xen security issue, but it matters for hardening PV frontends\nagainst malicious backends (confidential and disaggregated deployments)."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The bug is reached when a malicious Xen PVCalls backend writes crafted responses into the shared grant-table ring and notifies the guest frontend via an inter-domain event channel; this is an adjacent on-host backend-to-guest path, not remote IP delivery to the guest.\nAC:L - A compromised backend fully controls ring response contents and can set any req_id (including 0xffffffff for rsp[-1]) and re-notify the frontend IRQ at will; no races or attacker-uncontrollable heap layout are required to trigger the out-of-bounds write.\nPR:N - No credentials inside the vulnerable guest are needed; once the pvcalls frontend is xenbus-connected to a backend, that backend alone can inject the malformed response. Backend/domain control is the attack position, not privileges obtainable in the guest via user namespaces.\nUI:N - No victim user or application action is required after xenbus binds the pvcalls frontend to its backend; backend-driven ring writes and event-channel interrupts alone reach pvcalls_front_event_handler() without mounts, socket use, or other interactive steps.\nS:U - The out-of-bounds write corrupts kmalloc heap memory and kernel objects within the guest running the pvcalls frontend. This is backend-to-guest hardening, not a demonstrated guest-to-host or hypervisor escape across the VM security boundary.\nC:H - Backend-chosen req_id indexes bedata-\u003ersp[] out of bounds for a ~20-byte memcpy plus req_id store, corrupting adjacent kernel heap memory (including rsp[-1] via the signed req_id bug) and enabling plausible arbitrary kernel memory disclosure if shaped further.\nI:H - The heap out-of-bounds write can overwrite adjacent kmalloc objects or allocator metadata, providing a credible path to arbitrary guest-kernel memory modification and control-flow hijack rather than being limited to a bounded or non-security integrity effect.\nA:H - Corrupting kernel heap structures via the unbounded rsp[] indexing can immediately panic or oops the guest kernel; even unexploited attempts are likely to crash or disable the frontend, causing total loss of guest availability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:30.909Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d1297a9e2fd6ce08678b370d41bc980ca798f809"
        },
        {
          "url": "https://git.kernel.org/stable/c/d33846c8dcc06b83b7acdeac1e8bfbb5c0c26cb2"
        }
      ],
      "title": "xen/pvcalls: bound backend response req_id before indexing rsp[]",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72380",
    "datePublished": "2026-08-15T05:56:12.866Z",
    "dateReserved": "2026-08-09T03:40:39.922Z",
    "dateUpdated": "2026-08-17T05:43:30.909Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}