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CVE-2026-89486 (GCVE-0-2026-89486)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-13 06:29
VLAI
Title
ipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user()
Summary
In the Linux kernel, the following vulnerability has been resolved: ipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user() Commit 9e91f8a6c868 ("ipmi:msghandler: Remove srcu for the ipmi_interfaces list") dropped the synchronize_rcu() between unlinking the command receivers from intf->cmd_rcvrs and freeing them, updating only the comment that explains why the barrier is needed. The cmd_rcvrs list is still traversed under plain RCU: find_cmd_rcvr() walks it inside rcu_read_lock(), and handle_ipmb_get_msg_cmd() borrows rcvr->user from that lookup within the same read-side section. Without the grace period, _ipmi_destroy_user() can kfree() a cmd_rcvr while a reader still holds a pointer to it, causing a use-after-free. The rework only made srcu unnecessary for the interfaces list; the cmd_rcvrs list still relies on plain RCU. Restore the synchronize_rcu() before freeing the receivers.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9e91f8a6c8688e27f4ccce7db457da87d6458836 , < 3088e41292fecf132f85f79af5ee4d620b9ff1b4 (git)
Affected: 9e91f8a6c8688e27f4ccce7db457da87d6458836 , < 5dc0b2a9af95a97861c1bffaf1687a3173e395c5 (git)
Affected: 9e91f8a6c8688e27f4ccce7db457da87d6458836 , < 05ec76cfbce653e07cec19b9b8b20e33449d5d87 (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (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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          "product": "Linux",
          "programFiles": [
            "drivers/char/ipmi/ipmi_msghandler.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user()\n\nCommit 9e91f8a6c868 (\"ipmi:msghandler: Remove srcu for the\nipmi_interfaces list\") dropped the synchronize_rcu() between unlinking\nthe command receivers from intf-\u003ecmd_rcvrs and freeing them, updating\nonly the comment that explains why the barrier is needed.\n\nThe cmd_rcvrs list is still traversed under plain RCU: find_cmd_rcvr()\nwalks it inside rcu_read_lock(), and handle_ipmb_get_msg_cmd() borrows\nrcvr-\u003euser from that lookup within the same read-side section. Without\nthe grace period, _ipmi_destroy_user() can kfree() a cmd_rcvr while a\nreader still holds a pointer to it, causing a use-after-free.\n\nThe rework only made srcu unnecessary for the interfaces list; the\ncmd_rcvrs list still relies on plain RCU. Restore the synchronize_rcu()\nbefore freeing the receivers."
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              "value": "AV:L - The UAF is reached by close/release on /dev/ipmiN (ipmi_release \u2192 ipmi_destroy_user \u2192 _ipmi_destroy_user) after IPMICTL_REGISTER_FOR_CMD; BMC GET_MSG/IPMB/LAN command delivery is the RCU reader, not Linux network-packet processing, so the attack remains local like other /dev/ipmiN IPMI bugs.\nAC:L - The attacker controls the free side (open, register-for-cmd, close) and arms command watching, then races close against GET_MSG/IPMB/LAN command handling they can induce via their own IPMI ioctls and typical host-to-BMC access; this is an attacker-driven UAF race, not a layout or victim-state condition.\nPR:L - ipmi_open, ipmi_create_user, and IPMICTL_REGISTER_FOR_CMD perform no capable() check; access is only DAC on /dev/ipmiN, which server and appliance deployments routinely grant to a non-root ipmi/management group for ipmitool/freeipmi, matching established IPMI scoring.\nUI:N - The attacker opens, registers, and closes their own /dev/ipmiN file descriptors and issues ioctls themselves; no victim action such as mounting a filesystem or opening a hostile file is required.\nS:U - This is a host-kernel heap use-after-free of struct cmd_rcvr in the IPMI message handler; impact stays in the same OS security authority with no VM escape, IOMMU bypass, or sandbox boundary crossing.\nC:H - Without synchronize_rcu(), find_cmd_rcvr() and handle_*_get_msg_cmd() read rcvr-\u003euser from a kmalloc\u0027d cmd_rcvr that _ipmi_destroy_user() already kfree()d; reclaiming that object yields an attacker-controlled pointer and a kernel read primitive, so confidentiality is High per UAF guidance.\nI:H - A sprayed cmd_rcvr supplies a fake ipmi_user pointer; ipmi_alloc_recv_msg() then updates nr_msgs/refcount through that pointer and smi_work later invokes user-\u003ehandler-\u003eipmi_recv_hndl, enabling heap spray and control-flow hijack for arbitrary write and code execution.\nA:H - Use-after-free of cmd_rcvr during the RCU list walk and the subsequent dangling user-pointer dereference readily oopses or panics the kernel under poisoning/KASAN, so availability impact is High per UAF guidance."
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    "datePublished": "2026-09-11T19:43:40.116Z",
    "dateReserved": "2026-09-11T19:38:34.712Z",
    "dateUpdated": "2026-09-13T06:29:55.269Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-13T06:56:15+00:00",
      "cve": "CVE-2026-89486",
      "id": "CVE-2026-89486",
      "initial_release_date": "2026-09-11T19:43:40.116000+00:00",
      "product_status:known_affected": "2",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel IPMI: Use-after-free vulnerability leading to system instability or privilege escalation.",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89486.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-16T00:03:04Z",
      "cve": "CVE-2026-89486",
      "id": "CVE-2026-89486",
      "initial_release_date": "2026-09-12T16:27:37Z",
      "product_status:known_not_affected": "353",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89486",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89486.json",
      "version": "5"
    }
  }
}



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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.

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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.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • 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.


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