CVE-2026-89657 (GCVE-0-2026-89657)
Vulnerability from cvelistv5
Published
2026-09-11 19:45
Modified
2026-10-19 08:50
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: libceph: validate OSD extent maps before cursor advance net/ceph/osd_client.c:osd_sparse_read() validates that the sparse-read data length matches the summed extent lengths, but it does not validate that each OSD-supplied extent is monotonic and lies inside the original request range. A malformed authenticated OSD reply can advertise a far-forward nonzero extent offset with a matching data length and make the client advance the message-data cursor beyond the request buffer. This reaches the BUG_ON(!*length) assertion in ceph_msg_data_next() from the client receive path. Impact: A malicious or compromised authenticated Ceph OSD peer can crash a kernel Ceph client via a malformed sparse-read reply. Reject sparse extent maps that overflow, move backwards, overlap, or extend outside the original sparse-read request before advancing the cursor. [ idryomov: perform sparse_extent_map_valid() check a bit earlier, in CEPH_SPARSE_READ_DATA_LEN instead of CEPH_SPARSE_READ_DATA_PRE state ]
References
Impacted products
Vendor Product Version
Linux Linux Version: f628d799972799023d32c2542bb2639eb8c4f84e
Version: f628d799972799023d32c2542bb2639eb8c4f84e
Version: f628d799972799023d32c2542bb2639eb8c4f84e
Version: f628d799972799023d32c2542bb2639eb8c4f84e
Version: f628d799972799023d32c2542bb2639eb8c4f84e
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{
  "containers": {
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          "programFiles": [
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      "cpeApplicability": [
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          "nodes": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: validate OSD extent maps before cursor advance\n\nnet/ceph/osd_client.c:osd_sparse_read() validates that the sparse-read\ndata length matches the summed extent lengths, but it does not validate\nthat each OSD-supplied extent is monotonic and lies inside the original\nrequest range. A malformed authenticated OSD reply can advertise a\nfar-forward nonzero extent offset with a matching data length and make\nthe client advance the message-data cursor beyond the request buffer.\nThis reaches the BUG_ON(!*length) assertion in ceph_msg_data_next() from\nthe client receive path.\n\nImpact: A malicious or compromised authenticated Ceph OSD peer can crash\na kernel Ceph client via a malformed sparse-read reply.\n\nReject sparse extent maps that overflow, move backwards, overlap, or\nextend outside the original sparse-read request before advancing the\ncursor.\n\n[ idryomov: perform sparse_extent_map_valid() check a bit earlier,\n  in CEPH_SPARSE_READ_DATA_LEN instead of CEPH_SPARSE_READ_DATA_PRE\n  state ]"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The malformed sparse-read extent map is consumed in osd_sparse_read() on the Ceph messenger TCP receive path (messenger_v1/v2) when a kernel CephFS client handles an MOSDOpReply from a remote OSD; no local syscall or ioctl is required to parse the reply.\nAC:L - A malicious OSD fully controls the sparse extent offsets and lengths and can advertise a far-forward nonzero extent with a matching data length, deterministically advancing the message-data cursor past the request buffer into BUG_ON(!*length) in ceph_msg_data_next() with no race or special memory layout.\nPR:N - The attacker acts as a remote Ceph OSD peer on a compromised or attacker-controlled cluster and needs no account, capabilities, or user-namespace privileges on the victim Linux host; any kernel CephFS client connected to that cluster is exposed.\nUI:N - Once CephFS is mounted with fscrypt-encrypted files or the sparseread option, netfs/buffered reads and encrypted RMW writes issue CEPH_OSD_OP_SPARSE_READ as normal I/O; the OSD can crash the client on the next such reply without further victim action at exploit time.\nS:U - The BUG_ON panic occurs in the kernel Ceph client\u0027s receive path on the same host and does not cross a VM, IOMMU, or sandbox boundary to another security authority.\nC:N - ceph_msg_data_next() hits BUG_ON(!*length) and related cursor assertions when the buffer is exhausted, before any out-of-bounds page access; there is no use-after-free, OOB read, or other information-disclosure primitive.\nI:N - Cursor over-advance is stopped by BUG_ON assertions rather than writing past the allocated request pages; hole-zeroing via zero_user_segment stays inside the destination buffer until the panic, so there is no arbitrary kernel write or control-flow hijack.\nA:H - BUG_ON(!*length) in ceph_msg_data_next() on the client receive path causes a kernel oops or panic, fully denying availability of the affected Ceph client host until reboot."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:50:28.836Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/94ae5145c520618802b0a24c047dcd5f05835db8"
        },
        {
          "url": "https://git.kernel.org/stable/c/058ffa81f9440c5b4714685611cf697fd3739ec9"
        },
        {
          "url": "https://git.kernel.org/stable/c/2571b35883268a266554e80d368e67fdfea7fb9d"
        },
        {
          "url": "https://git.kernel.org/stable/c/201db408872ca12cf09e36bf0f560138c3dcfa1c"
        },
        {
          "url": "https://git.kernel.org/stable/c/9ec08b7499a62c6d4afa93d36ab47a43fcad57d1"
        }
      ],
      "title": "libceph: validate OSD extent maps before cursor advance",
      "x_generator": {
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      }
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89657",
    "datePublished": "2026-09-11T19:45:46.118Z",
    "dateReserved": "2026-09-11T19:38:34.743Z",
    "dateUpdated": "2026-10-19T08:50:28.836Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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