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CVE-2026-89549

Status: ReceivedHigh (7.5)—

In the Linux kernel, the following vulnerability has been resolved:

sunrpc: route to a populated pool in svc_pool_for_cpu()

svc_set_num_threads() spreads the requested threads evenly across the service's pools (base = nrservs / sv_nrpools). When a service runs fewer threads than it has pools -- e.g. an nfsd configured with fewer threads than the host has NUMA nodes while running in "pernode" or "percpu" mode -- the trailing pools are left with no threads at all.

svc_xprt_enqueue() selects a pool from the CPU servicing the transport, queues the transport on that pool's sp_xprts, and only wakes a thread from the same pool.

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Each thread services exclusively its own pool, so a transport that lands on a threadless pool is enqueued on sp_xprts and never picked up: the connection hangs indefinitely.

Have svc_pool_for_cpu() skip pools that currently have no threads, falling back to the next populated pool. This trades NUMA locality for a guarantee that the work is actually serviced. sp_nrthreads is only updated under the service mutex; the lockless read here is a best-effort routing hint, so annotate it with data_race().

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

Inferred by deterministic rules from the CVSS vector and CWE. Indicative only.

🛡️ ATT&CK mitigations that cover these techniques

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Linux — Linux KernelAI

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-89549",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "bfd241600a3b0db4fe43c859f1460d0a958d924a",
              "lessThan": "9accc25e5af0bac8479f6054e674b2c593c45281",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "bfd241600a3b0db4fe43c859f1460d0a958d924a",
              "lessThan": "6f66d38e2a6c78d48723ea17ad86135ec80ca24b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "bfd241600a3b0db4fe43c859f1460d0a958d924a",
              "lessThan": "d79d7b9e8acbb53e2d60f6b24afc13e2f15e691f",
              "versionType": "git"
            },
            {
              "status": "affected",
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              "lessThan": "edb20e8c03aebacb409968c99d046f509c6c485a",
              "versionType": "git"
            },
            {
              "status": "affected",
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              "lessThan": "011479cf9a7657d4a3e7cc42a784ac63df594170",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "bfd241600a3b0db4fe43c859f1460d0a958d924a",
              "lessThan": "9d04d64ad192439835ed9884d767353061c3ed6f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "bfd241600a3b0db4fe43c859f1460d0a958d924a",
              "lessThan": "8f766d2d0b4dabf54f8b35812df2b4f481d13316",
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            {
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              "lessThan": "f6310491c4cdb88af73aa551ec9df1f10a90c709",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/sunrpc/svc.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.19"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "2.6.19",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/sunrpc/svc.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:38.373",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/011479cf9a7657d4a3e7cc42a784ac63df594170",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6f66d38e2a6c78d48723ea17ad86135ec80ca24b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/8f766d2d0b4dabf54f8b35812df2b4f481d13316",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9accc25e5af0bac8479f6054e674b2c593c45281",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9d04d64ad192439835ed9884d767353061c3ed6f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/d79d7b9e8acbb53e2d60f6b24afc13e2f15e691f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/edb20e8c03aebacb409968c99d046f509c6c485a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f6310491c4cdb88af73aa551ec9df1f10a90c709",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: route to a populated pool in svc_pool_for_cpu()\n\nsvc_set_num_threads() spreads the requested threads evenly across the\nservice's pools (base = nrservs / sv_nrpools).  When a service runs\nfewer threads than it has pools -- e.g. an nfsd configured with fewer\nthreads than the host has NUMA nodes while running in \"pernode\" or\n\"percpu\" mode -- the trailing pools are left with no threads at all.\n\nsvc_xprt_enqueue() selects a pool from the CPU servicing the transport,\nqueues the transport on that pool's sp_xprts, and only wakes a thread\nfrom the same pool.  Each thread services exclusively its own pool, so a\ntransport that lands on a threadless pool is enqueued on sp_xprts and\nnever picked up: the connection hangs indefinitely.\n\nHave svc_pool_for_cpu() skip pools that currently have no threads,\nfalling back to the next populated pool.  This trades NUMA locality for\na guarantee that the work is actually serviced.  sp_nrthreads is only\nupdated under the service mutex; the lockless read here is a best-effort\nrouting hint, so annotate it with data_race()."
    }
  ],
  "lastModified": "2026-09-14T13:19:09.857",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}