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CVE-2026-89657 (GCVE-0-2026-89657)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-14 12:01
VLAI
Title
libceph: validate OSD extent maps before cursor advance
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 ]
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f628d799972799023d32c2542bb2639eb8c4f84e , < 94ae5145c520618802b0a24c047dcd5f05835db8 (git)
Affected: f628d799972799023d32c2542bb2639eb8c4f84e , < 058ffa81f9440c5b4714685611cf697fd3739ec9 (git)
Affected: f628d799972799023d32c2542bb2639eb8c4f84e , < 2571b35883268a266554e80d368e67fdfea7fb9d (git)
Affected: f628d799972799023d32c2542bb2639eb8c4f84e , < 201db408872ca12cf09e36bf0f560138c3dcfa1c (git)
Affected: f628d799972799023d32c2542bb2639eb8c4f84e , < 9ec08b7499a62c6d4afa93d36ab47a43fcad57d1 (git)
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Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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          "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 ]"
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              "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."
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    "datePublished": "2026-09-11T19:45:46.118Z",
    "dateReserved": "2026-09-11T19:38:34.743Z",
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    "state": "PUBLISHED"
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    "redhat_vex": {
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      "current_release_date": "2026-09-13T06:51:18+00:00",
      "cve": "CVE-2026-89657",
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      "title": "kernel: libceph: Denial of Service in Linux kernel via malformed sparse-read replies",
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      "version": "3"
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    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-16T00:00:58Z",
      "cve": "CVE-2026-89657",
      "id": "CVE-2026-89657",
      "initial_release_date": "2026-09-12T16:24:07Z",
      "product_status:known_affected": "168",
      "product_status:known_not_affected": "185",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89657",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89657.json",
      "version": "4"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.