CVE-2026-72220 (GCVE-0-2026-72220)
Vulnerability from cvelistv5
Published
2026-08-15 05:54
Modified
2026-08-17 05:41
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: sunrpc: harden rq_procinfo lifecycle to prevent double-free The svc_release_rqst() function executes the callback inside rqstp->rq_procinfo->pc_release. However, if a worker thread begins processing a new request and encounters an early error path (e.g., unsupported protocol, short frame, or bad auth) before a valid rq_procinfo is installed, a stale release hook can be re-triggered against reused state from the previous RPC, resulting in a double-free or use-after-free vulnerability. Harden the lifecycle of rq_procinfo by: 1. Ensuring svc_release_rqst() always clears rq_procinfo after the optional pc_release() call, regardless of whether the hook exists. 2. Explicitly clearing rq_procinfo at request entry in svc_process() before any early decode or drop paths. 3. Ensuring svc_process_bc() does the same at backchannel entry. This guarantees that error flows will not encounter a non-NULL stale rq_procinfo pointer when there is nothing to release.
Impacted products
Vendor Product Version
Linux Linux Version: d9adbb6e10bf7d4223d3d521ede1b2052903bc5e
Version: d9adbb6e10bf7d4223d3d521ede1b2052903bc5e
Version: d9adbb6e10bf7d4223d3d521ede1b2052903bc5e
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sunrpc/svc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "d9adbb6e10bf7d4223d3d521ede1b2052903bc5e",
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              "versionType": "git"
            }
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        {
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          "product": "Linux",
          "programFiles": [
            "net/sunrpc/svc.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.18"
            },
            {
              "lessThan": "6.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "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": "6.18.40",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "7.2",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: harden rq_procinfo lifecycle to prevent double-free\n\nThe svc_release_rqst() function executes the callback inside\nrqstp-\u003erq_procinfo-\u003epc_release. However, if a worker thread begins\nprocessing a new request and encounters an early error path (e.g.,\nunsupported protocol, short frame, or bad auth) before a valid\nrq_procinfo is installed, a stale release hook can be re-triggered\nagainst reused state from the previous RPC, resulting in a double-free\nor use-after-free vulnerability.\n\nHarden the lifecycle of rq_procinfo by:\n1. Ensuring svc_release_rqst() always clears rq_procinfo after the\n   optional pc_release() call, regardless of whether the hook exists.\n2. Explicitly clearing rq_procinfo at request entry in svc_process()\n   before any early decode or drop paths.\n3. Ensuring svc_process_bc() does the same at backchannel entry.\n\nThis guarantees that error flows will not encounter a non-NULL stale\nrq_procinfo pointer when there is nothing to release."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The flaw is in server-side SUNRPC request handling reached from remote RPC over TCP/UDP/RDMA transports used by nfsd and lockd (svc_recv\u2192svc_handle_xprt\u2192svc_process), exploitable by sending crafted ONC/RPC packets to listening NFS/NLM ports.\nAC:L - An attacker controls the RPC sequence and timing (valid request then malformed/short/bad-auth/bad-prog packet on the same pooled worker) to reliably re-trigger a stale pc_release without depending on uncontrollable layout or victim state.\nPR:N - Trigger paths include pre-authentication failures (garbage credentials, unknown program/version, short frames) that still call svc_release_rqst; stale rq_procinfo can be left by any prior RPC on the same worker, so no attacker credentials are required.\nUI:N - Exploitation requires only network RPC traffic to an already-running NFS/NLM server; no end-user actions such as mounting a share or opening files are needed beyond normal server exposure.\nS:U - Impact is kernel heap corruption and privilege escalation within the host kernel context; it does not inherently cross a VM, container, or IOMMU security boundary to another authority.\nC:H - The bug is an explicit double-free/use-after-free of per-request NFS release state (e.g. nfsd4_release_compoundargs kfree/vfree chains and fh_put paths), enabling arbitrary kernel memory disclosure when exploited.\nI:H - Re-invoking pc_release on reused svc_rqst buffers corrupts heap metadata and object lifetimes, providing a standard kernel double-free/UAF primitive suitable for arbitrary write and code execution.\nA:H - Repeated or mistimed pc_release calls can immediately panic the kernel via SLUB double-free detection, oops, or wedged nfsd worker threads, causing complete loss of availability on NFS-serving systems."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:41:41.598Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/66014ab165cb01bfef5836939412a8ef98d5d5ff"
        },
        {
          "url": "https://git.kernel.org/stable/c/31ba490c02d476a5e4f90b8845932ac9db8aa71b"
        },
        {
          "url": "https://git.kernel.org/stable/c/18d216788bef06332ff8901670ecf1ed8f6eb614"
        }
      ],
      "title": "sunrpc: harden rq_procinfo lifecycle to prevent double-free",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72220",
    "datePublished": "2026-08-15T05:54:13.800Z",
    "dateReserved": "2026-08-09T03:40:39.913Z",
    "dateUpdated": "2026-08-17T05:41:41.598Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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