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CVE-2026-89653 (GCVE-0-2026-89653)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-14 12:01
VLAI
Title
ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode
Summary
In the Linux kernel, the following vulnerability has been resolved: ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode MDSMap export_targets entries are monitor controlled. check_new_map() uses each entry as a bit number in a fixed stack bitmap, so a rank outside the protocol namespace can make set_bit() write past the end of the array. Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not validate against possible_max_rank here because maps may legitimately reference ranks beyond a temporarily reduced max_mds.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: d517b3983dd3106ca92d6c5d0d09415a4a09481c , < 3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe (git)
Affected: d517b3983dd3106ca92d6c5d0d09415a4a09481c , < 8c823bbab3c24e657469a84db96902ba82d4e8bb (git)
Affected: d517b3983dd3106ca92d6c5d0d09415a4a09481c , < c4addccd05bacbef2144b4db14853d0308a218ac (git)
Affected: d517b3983dd3106ca92d6c5d0d09415a4a09481c , < 736adee11af36e407ed902264f8b2fb5cf94b62f (git)
Affected: d517b3983dd3106ca92d6c5d0d09415a4a09481c , < 4d298880f82c42383b36946bafde7ccf4d804c9b (git)
Affected: d517b3983dd3106ca92d6c5d0d09415a4a09481c , < 96c3f5fbb0d5386e7111426f047f98cec4586674 (git)
Affected: d517b3983dd3106ca92d6c5d0d09415a4a09481c , < aedc9053d909508a5f56c3f49f885fc030df4730 (git)
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Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 5.15.221 , ≤ 5.15.* (semver)
Unaffected: 6.1.188 , ≤ 6.1.* (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)
guessed Create a notification for this product.
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          "product": "Linux",
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: reject export_targets ranks \u003e= CEPH_MAX_MDS in mdsmap decode\n\nMDSMap export_targets entries are monitor controlled. check_new_map()\nuses each entry as a bit number in a fixed stack bitmap, so a rank\noutside the protocol namespace can make set_bit() write past the end of\nthe array.\n\nReject ranks outside CEPH_MAX_MDS while decoding the map. Do not\nvalidate against possible_max_rank here because maps may legitimately\nreference ranks beyond a temporarily reduced max_mds."
        }
      ],
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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              "value": "AV:N - A crafted MDSMap arrives in CEPH_MSG_MDS_MAP over the Ceph messenger TCP session from a monitor or MDS; extra_mon_dispatch() and mds_dispatch() deliver it to ceph_mdsc_handle_mdsmap() on already-mounted CephFS/Rook/Kubernetes clients without a local syscall.\nAC:L - The monitor fully controls each export_targets[] u32; after the first map is stored, a later epoch reaches check_new_map() and set_bit() with an attacker-chosen bit number, overflowing the stack bitmap with no race or special layout.\nPR:N - The attacker is the remote Ceph monitor or MDS peer and needs no Linux UID, capability, or init-namespace root on the victim, matching other Ceph client decode CVEs such as CVE-2026-68159.\nUI:N - Once CephFS is mounted, MDS maps are subscribed and applied automatically in the ceph-msgr worker; a malicious peer can push a new epoch without any further interactive victim action.\nS:U - The stack out-of-bounds write corrupts kernel memory on the Ceph client host only and does not cross a VM, IOMMU, or sandbox security authority.\nC:H - set_bit() with an attacker-chosen rank writes past the fixed stack bitmap in check_new_map(), corrupting adjacent kernel stack contents; this memory-corruption primitive can be leveraged for information disclosure.\nI:H - The overflow is a stack out-of-bounds write of attacker-selected bits at a u32-controlled offset from the targets[] array, enabling control-flow hijack and arbitrary kernel writes.\nA:H - An out-of-range bit index makes set_bit() write off the stack object, causing a KASAN stack-out-of-bounds report or kernel oops/panic that a malicious monitor can repeat with each new map epoch."
            }
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89653",
    "datePublished": "2026-09-11T19:45:43.261Z",
    "dateReserved": "2026-09-11T19:38:34.742Z",
    "dateUpdated": "2026-09-14T12:01:48.132Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
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      "date": "2026-09-15",
      "epss": "0.00509",
      "percentile": "0.41983"
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      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "ceph: reject export_targets ranks \u003e= CEPH_MAX_MDS in mdsmap decode",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-89653.json",
      "version": "2"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-13T07:00:11+00:00",
      "cve": "CVE-2026-89653",
      "id": "CVE-2026-89653",
      "initial_release_date": "2026-09-11T19:45:43.261000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ceph: Linux kernel (Ceph): Denial of Service via out-of-bounds write in mdsmap decode",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89653.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-13T16:57:31Z",
      "cve": "CVE-2026-89653",
      "id": "CVE-2026-89653",
      "initial_release_date": "2026-09-12T16:24:10Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89653",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89653.json",
      "version": "3"
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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