{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "e4500b5e35c213e0f97be7cb69328c0877203a79"
            },
            {
              "fixed": "091137821e1fc88f37e15201abf055c9494ddc61"
            },
            {
              "fixed": "01542430081014d80fc9e70e92d6647432ddb7fc"
            },
            {
              "fixed": "23eb34a53a53cb1a6dab1eeee830633207ac158d"
            },
            {
              "fixed": "19f16f04c2b014a7dd214dc1e42557d8530b16f3"
            },
            {
              "fixed": "2701431aa3cc8b23efe6890182e7b04f5e76fab5"
            },
            {
              "fixed": "fe46746087b5b9c5bb2d022df6c7819218494ced"
            },
            {
              "fixed": "2dba24dcd5050be4b7b119e6f0b01f62203b5d26"
            },
            {
              "fixed": "7af4c4f01305b0935adf6d4301b1ec407025485d"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.8.0"
            },
            {
              "fixed": "5.10.270"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.221"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.188"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.157"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "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-2026-89655.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock\n\nlist_for_each_entry() iterates ci-\u003ei_cap_flush_list but drops\ni_ceph_lock to send cap messages.  During the unlock window,\nhandle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries\nwith tid \u003c= flush_tid from the list, release i_ceph_lock, and free\nthem via ceph_free_cap_flush() outside any lock.  When the original\nthread reacquires i_ceph_lock and the for-loop macro advances via\ncf = list_next_entry(cf, i_list), it dereferences cf-\u003ei_list.next\non freed memory.\n\nThe race timeline:\n\n  __kick_flushing_caps()              handle_cap_flush_ack()\n  -----------------------             -----------------------\n  holds i_ceph_lock        \u003c---\n  iterates to cf (tid=10)\n  prepares FLUSH message\n  drops i_ceph_lock        \u003c---\n  __send_cap() ── FLUSH(tid=10)\n\t                              MDS sends FLUSH_ACK(tid=10)\n                           ---\u003e       acquires i_ceph_lock\n                                      cf-\u003etid(10) \u003c= flush_tid(10),\n                                      detaches cf from i_cap_flush_list\n                                      drops i_ceph_lock\n                                      ceph_free_cap_flush(cf) \u003c- frees it!\n  acquires i_ceph_lock     \u003c---\n  for-loop advances:\n    cf = list_next_entry(cf, i_list)\n      -- UAF on freed cf-\u003ei_list.next\n\nThe cf was just sent by __kick_flushing_caps itself via __send_cap().\nThe MDS may respond with FLUSH_ACK quickly enough that\nhandle_cap_flush_ack() frees cf before __kick_flushing_caps can\nfinish the iteration.\n\nFix by converting to a manual while loop: save the next pointer\nunder i_ceph_lock before dropping it, then use the saved pointer\nafter reacquiring, so the potentially-freed cf is never accessed again.",
  "id": "CVE-2026-89655",
  "modified": "2026-09-15T03:30:36.849525855Z",
  "published": "2026-09-11T19:45:44.841Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/01542430081014d80fc9e70e92d6647432ddb7fc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/091137821e1fc88f37e15201abf055c9494ddc61"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/19f16f04c2b014a7dd214dc1e42557d8530b16f3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/23eb34a53a53cb1a6dab1eeee830633207ac158d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2701431aa3cc8b23efe6890182e7b04f5e76fab5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2dba24dcd5050be4b7b119e6f0b01f62203b5d26"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7af4c4f01305b0935adf6d4301b1ec407025485d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fe46746087b5b9c5bb2d022df6c7819218494ced"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89655.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89655"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock"
}