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CVE-2026-31535

Status: AnalyzedMedium (4.7)—

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

smb: client: make use of smbdirect_socket.recv_io.credits.available

The logic off managing recv credits by counting posted recv_io and granted credits is racy.

That's because the peer might already consumed a credit, but between receiving the incoming recv at the hardware and processing the completion in the 'recv_done' functions we likely have a window where we grant credits, which don't really exist.

So we better have a decicated counter for the available credits, which will be incremented when we posted new recv buffers and drained when we grant the credits to the peer.

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).

Affected technologies (1)

Linux — Linux Kernel

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-31535",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
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        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.7,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1
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    ]
  },
  "affected": [
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              "status": "unaffected",
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              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
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          ],
          "programFiles": [
            "fs/smb/client/smbdirect.c"
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  ],
  "published": "2026-04-24T15:16:27.427",
  "references": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "tags": [
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      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-367"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: make use of smbdirect_socket.recv_io.credits.available\n\nThe logic off managing recv credits by counting posted recv_io and\ngranted credits is racy.\n\nThat's because the peer might already consumed a credit,\nbut between receiving the incoming recv at the hardware\nand processing the completion in the 'recv_done' functions\nwe likely have a window where we grant credits, which\ndon't really exist.\n\nSo we better have a decicated counter for the\navailable credits, which will be incremented\nwhen we posted new recv buffers and drained when\nwe grant the credits to the peer."
    }
  ],
  "lastModified": "2026-06-17T10:33:55.907",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "versionEndExcluding": "6.18.11",
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            {
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          "operator": "OR"
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}