{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "d463a43d69f4af85887671d76182437775fd1631"
            },
            {
              "fixed": "3bf7dba8dba9a05774b846affec61a3624ddba38"
            },
            {
              "fixed": "58c2d3e954c13694ef6e820a5e9456461bb9e7df"
            },
            {
              "fixed": "332c444f4dc6fa1e8b8637c9e82d29e97f768656"
            },
            {
              "fixed": "a3eb169ee297aa99670ba927c659990bd1e453f3"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.7.0"
            },
            {
              "fixed": "6.12.109"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.50"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89650.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound num_export_targets array for mds info v2/v3\n\nceph_mdsmap_decode() in fs/ceph/mdsmap.c reads num_export_targets from\neach per-mds info record and advances the decode cursor by\nnum_export_targets * sizeof(u32) without first checking that many bytes\nremain. The only upper-bound check that catches a runaway cursor\n(*p \u003e info_end) is gated on info_v \u003e= 4, because info_end is left NULL\nfor info_v 2 and 3. When the monitor sends an MDS map whose per-mds\ninfo version is 2 or 3 with an oversized num_export_targets, the cursor\nmoves past the message front buffer and the later export-targets loop\ncalls the unchecked ceph_decode_32() on out-of-bounds memory.\n\nA kernel client processes CEPH_MSG_MDS_MAP from its monitor session\n(net/ceph/mon_client.c dispatches it; fs/ceph/super.c routes it to\nceph_mdsc_handle_mdsmap(), which sets end to the front buffer bound and\ncalls ceph_mdsmap_decode()). A malicious or compromised monitor, or an\non-path attacker on an unsigned/unencrypted messenger session, can\ntherefore drive an out-of-bounds read in the client kernel; on x86_64\nwith KASAN it is reported as a slab-out-of-bounds read in\nceph_mdsmap_decode(). The decoded values land in the internal\ninfo-\u003eexport_targets[] array, so the consequence is a kernel\nout-of-bounds read, not an information leak to the attacker.\n\nImpact: a malicious or compromised Ceph monitor sending an MDS map with\na per-mds info version of 2 or 3 and an oversized num_export_targets\nfield triggers an out-of-bounds read in the CephFS client kernel.\n\nAdd a ceph_decode_need() for the export-targets array before advancing\nthe cursor, so the bound is enforced for every info_v \u003e= 2, not only\ninfo_v \u003e= 4. This mirrors the count-then-need idiom already used for\nm_data_pg_pools later in the same function.\n\nCompute the export-targets byte count with size_mul() and reuse that\nchecked length when advancing the cursor, so the attacker-controlled\nnum_export_targets multiplication fails closed on overflow rather than\nrelying on the later kcalloc() guard.",
  "id": "CVE-2026-89650",
  "modified": "2026-09-13T03:30:25.333763147Z",
  "published": "2026-09-11T19:45:40.867Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/332c444f4dc6fa1e8b8637c9e82d29e97f768656"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3bf7dba8dba9a05774b846affec61a3624ddba38"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/58c2d3e954c13694ef6e820a5e9456461bb9e7df"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a3eb169ee297aa99670ba927c659990bd1e453f3"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89650.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89650"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "ceph: bound num_export_targets array for mds info v2/v3"
}