CVE-2026-89486

ipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user()

Published Sep 11, 2026 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed

Description

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.

Analysis

Technical impact

In the Linux kernel IPMI subsystem, a use‑after‑free bug occurs when the command‑receiver structure is freed while a reader still holds a reference to it. This race originates from the removal of the synchronize_rcu() barrier that previously separated the unlinking of command receivers from their deallocation, leaving the list traversed under plain RCU. The resulting memory corruption can compromise kernel memory integrity and may trigger a crash or unexpected behavior. The flaw is classified as CWE‑825, indicating a race condition that can lead to a use‑after‑free vulnerability. While the description does not explicitly state arbitrary code execution, the kernel memory corruption could potentially be leveraged to elevate privileges if an attacker can influence the dereferenced data.

Affected Systems

The affected product is the generic Linux kernel build that includes the legacy IPMI interface code without the commit restoring the synchronize_rcu() barrier. No specific vendor or product variants are listed, and affected kernel versions are not enumerated, so any kernel containing the vulnerable code should be considered at risk.

Risk and Exploitability

The CVSS score of 7.8 indicates a high severity, while the EPSS score of <1% suggests a low probability of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. Based on the description, it is inferred that an attacker would need to have the ability to send IPMI commands to the target’s BMC to trigger the flaw. If such access is achieved, the memory corruption could enable the attacker to interfere with kernel execution paths or elevate privileges.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`9e91f8a6c8688e27f4ccce7db457da87d6458836`	affected	< 3088e41292fecf132f85f79af5ee4d620b9ff1b4
`9e91f8a6c8688e27f4ccce7db457da87d6458836`	affected	< 5dc0b2a9af95a97861c1bffaf1687a3173e395c5
`9e91f8a6c8688e27f4ccce7db457da87d6458836`	affected	< 05ec76cfbce653e07cec19b9b8b20e33449d5d87

Linux

affected

Version	Status	Constraints
`6.16`	affected	—
`0`	unaffected	< 6.16
`6.18.50`	unaffected	≤ 6.18.*
`7.2.4`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[9e91f8a6c8688e27f4ccce7db457da87d6458836,3088e41292fecf132f85f79af5ee4d620b9ff1b4)`	affected	code_commit	—
`[9e91f8a6c8688e27f4ccce7db457da87d6458836,5dc0b2a9af95a97861c1bffaf1687a3173e395c5)`	affected	code_commit	—
`[9e91f8a6c8688e27f4ccce7db457da87d6458836,05ec76cfbce653e07cec19b9b8b20e33449d5d87)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`6.16`	affected	generic	—
`[0,6.16)`	unaffected	generic	—
`[6.18.50,6.19.0)`	unaffected	semver	—
`[7.2.4,7.3.0)`	unaffected	semver	—
`[7.3-rc1,*]`	unaffected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Apply a kernel update that includes the commit restoring the synchronize_rcu() barrier before freeing command receivers.
If the IPMI subsystem is not required, unload or disable the relevant IPMI kernel modules (e.g., ipmi_kcs, ipmi_msghandler) to eliminate the attack surface.
Restrict IPMI/BMC remote access to trusted interfaces or networks, or secure BMC credentials to prevent unauthorized command injection.

Generated by OpenCVE AI on September 15, 2026 at 22:43 UTC.

Tracking

Advisories

Source	ID	Title
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.124% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/05ec76cfbce653e07cec19b9b8b20e33449d5d87
https://git.kernel.org/stable/c/3088e41292fecf132f85f79af5ee4d620b9ff1b4
https://git.kernel.org/stable/c/5dc0b2a9af95a97861c1bffaf1687a3173e395c5
https://nvd.nist.gov/vuln/detail/CVE-2026-89486
https://www.cve.org/CVERecord?id=CVE-2026-89486

History

Sep 13, 2026 6:45 AM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:H'}`	cvssV3_1 `{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`

Sep 12, 2026 12:15 PM Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-825
References		https://nvd.nist.gov/vuln/detail/CVE-2026-89486 https://www.cve.org/CVERecord?id=CVE-2026-89486
Metrics	threat_severity `None`	cvssV3_1 `{'score': 6.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:H'}` threat_severity `Moderate`

Sep 11, 2026 11:45 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		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.
Title		ipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user()
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/05ec76cfbce653e07cec19b9b8b20e33449d5d87 https://git.kernel.org/stable/c/3088e41292fecf132f85f79af5ee4d620b9ff1b4 https://git.kernel.org/stable/c/5dc0b2a9af95a97861c1bffaf1687a3173e395c5