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CVE-2026-89656

Status: ReceivedCritical (9.8)—

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

libceph: reject buckets with mismatched CRUSH ids

crush_decode() stores bucket data by array slot, and the mapper later derives the per-bucket workspace index from the decoded bucket id. A malformed map can therefore make one bucket reuse another bucket's workspace by encoding an id different from -1 - slot.

For uniform buckets, the second replica selection expands the source bucket's permutation into that aliased workspace buffer. If the source bucket is larger than the aliased bucket, the write runs past the smaller permutation array and can escape the kvmalloc'd CRUSH workspace. KASAN reports a slab OOB write of 4 bytes in bucket_perm_choose().

Read full descriptionShow less

Reject buckets whose encoded id does not match their array slot. Valid CRUSH maps already use the canonical negative id corresponding to the bucket slot, so this restores the invariant expected by work->work[-1 - in->id] without changing valid map behavior.

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.

Vector CVSS AV:N/AC:L/PR:N/UI:N indica explotación remota sin privilegios (T1190). El OOB write en kernel puede escalar privilegios (T1068) o causar DoS (T1499.004).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Filter Network TrafficApplication Isolation and SandboxingExploit ProtectionUpdate SoftwareVulnerability ScanningThreat Intelligence Program

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)

Show
{
  "id": "CVE-2026-89656",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "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": "66a0e2d579dbec5c676cfe446234ffebb267c564",
              "lessThan": "ee59040d6ed1a5f8d10d27174b8f32c90ca8e89a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "66a0e2d579dbec5c676cfe446234ffebb267c564",
              "lessThan": "baad5875fdd2f5e248250fc3519bb045d64f1716",
              "versionType": "git"
            },
            {
              "status": "affected",
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              "lessThan": "4aeb93daadf388e72073abc204312dd364eeb30a",
              "versionType": "git"
            },
            {
              "status": "affected",
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              "lessThan": "6e5c6ce252b1eccfd41670a5cf95ab44f7ba7022",
              "versionType": "git"
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            {
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          ],
          "programFiles": [
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          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.11"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.11",
              "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/ceph/osdmap.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:51.813",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/00562ccd4e88d092b9b851df50fad20442bfeb24",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3516a4131c4e45d62ee4e42e82c36930e8c1fbbd",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3cde4a8302301679937474a5f7a851394cc1bd11",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4aeb93daadf388e72073abc204312dd364eeb30a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6e5c6ce252b1eccfd41670a5cf95ab44f7ba7022",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/79900d978158b2d80eef952fc41b9e4dc58d7b83",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
      "url": "https://git.kernel.org/stable/c/baad5875fdd2f5e248250fc3519bb045d64f1716",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ee59040d6ed1a5f8d10d27174b8f32c90ca8e89a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: reject buckets with mismatched CRUSH ids\n\ncrush_decode() stores bucket data by array slot, and the mapper later\nderives the per-bucket workspace index from the decoded bucket id. A\nmalformed map can therefore make one bucket reuse another bucket's\nworkspace by encoding an id different from -1 - slot.\n\nFor uniform buckets, the second replica selection expands the source\nbucket's permutation into that aliased workspace buffer. If the source\nbucket is larger than the aliased bucket, the write runs past the smaller\npermutation array and can escape the kvmalloc'd CRUSH workspace. KASAN\nreports a slab OOB write of 4 bytes in bucket_perm_choose().\n\nReject buckets whose encoded id does not match their array slot. Valid\nCRUSH maps already use the canonical negative id corresponding to the\nbucket slot, so this restores the invariant expected by\nwork->work[-1 - in->id] without changing valid map behavior."
    }
  ],
  "lastModified": "2026-09-14T13:19:18.080",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}