CVE-2026-98366 - Vulnerability Details

- RDMA/rxe: validate access flags before swapping the MR's PD

Description

In the Linux kernel, the following vulnerability has been resolved:

RDMA/rxe: validate access flags before swapping the MR's PD

rxe_rereg_user_mr() reassigns mr->ibmr.pd first and only then
validates the IB_MR_REREG_ACCESS argument:

if (flags & IB_MR_REREG_PD) {
rxe_put(old_pd);
rxe_get(pd);
mr->ibmr.pd = ibpd;
}

if (flags & IB_MR_REREG_ACCESS) {
if (access & ~RXE_ACCESS_SUPPORTED_MR)
return ERR_PTR(-EOPNOTSUPP);
mr->access = access;
}

Both flags pass the entry check because RXE_MR_REREG_SUPPORTED is
IB_MR_REREG_PD | IB_MR_REREG_ACCESS, so a caller can reach the access
check with mr->ibmr.pd already reassigned.

mr->ibmr.pd is owned by the core, which adjusts pd->usecnt only on the
success path: ib_uverbs_rereg_mr() jumps to put_new_uobj on a driver error
without undoing the reassignment, so mr->pd == new_pd while the usecnts
still charge the MR to orig_pd. ib_dereg_mr_user() then decrements
new_pd, whose count can reach zero while a memory window still references
it; uverbs_free_pd() frees the PD on that count alone and rxe_mw_cleanup()
writes to freed memory:

BUG: KASAN: slab-use-after-free in __rxe_put+0x31/0xa0
Write of size 4 at addr ffff8881301dd690 by task rxe_poc/591
__rxe_put+0x31/0xa0
rxe_mw_cleanup+0x42/0x200
__rxe_cleanup+0x115/0x370
rxe_dealloc_mw+0x4c/0x80
Allocated by task 591:
ib_uverbs_alloc_pd+0x258/0x540
Freed by task 591:
ib_dealloc_pd_user+0x174/0x210
uverbs_free_pd+0x8d/0xc0
ib_uverbs_dealloc_pd+0x18e/0x1d0

Validate the access flags before mutating any state so the callback either
applies every requested change or none.

Published: 2026-10-06

Score: 7.8 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

This flaw in the Linux kernel’s rxe driver lets a caller trigger a use‑after‑free in kernel memory. The flaw causes memory corruption that can lead to a denial of service by crashing the kernel or corrupting kernel data structures. No explicit arbitrary code execution was stated in the vulnerability description, but the memory corruption is a serious risk to kernel integrity.

Affected Systems

Linux kernels of all supported distributions that include the rxe RDMA driver are affected, as the vulnerability is present in the generic Linux kernel code. The specific versions impacted are those before the patch that enforces flag validation, as referenced in the kernel commit logs provided.

Risk and Exploitability

Based on the description, the likely attack vector involves a caller invoking RDMA operations that call rxe_rereg_user_mr. The CVSS score of 7.8 indicates high severity, reflecting the risk posed by the kernel use‑after‑free. The EPSS score of <1% indicates a very low probability of exploitation, and the vulnerability is not listed in the CISA KEV catalog. The impact is primarily a kernel memory corruption that could result in a denial of service.

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
`544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c`	affected	< 08f12745cb72981aa2cabe214af0c7a42a856f0a
`544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c`	affected	< 7230cc456d4bb2221c20c5f1d22b38b8576aa16f
`544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c`	affected	< fe602c91a52e161ace4afd5bdb8f33270c554c6f
`544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c`	affected	< 4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8
`544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c`	affected	< ae36a5b609ae79f4de966328b78d2584be9719a4

Linux

affected

Version	Status	Constraints
`6.5`	affected	—
`0`	unaffected	< 6.5
`6.6.158`	unaffected	≤ 6.6.*
`6.12.112`	unaffected	≤ 6.12.*
`6.18.54`	unaffected	≤ 6.18.*
`7.2.8`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c,08f12745cb72981aa2cabe214af0c7a42a856f0a)`	affected	code_commit	—
`[544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c,7230cc456d4bb2221c20c5f1d22b38b8576aa16f)`	affected	code_commit	—
`[544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c,fe602c91a52e161ace4afd5bdb8f33270c554c6f)`	affected	code_commit	—
`[544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c,4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8)`	affected	code_commit	—
`[544c7f62cf32db2bd358f1e8a40a98bf98fa2a5c,ae36a5b609ae79f4de966328b78d2584be9719a4)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`6.5`	affected	generic	—
`[0,6.5)`	unaffected	generic	—
`[6.6.158,6.7.0)`	unaffected	semver	—
`[6.12.112,6.13.0)`	unaffected	semver	—
`[6.18.54,6.19.0)`	unaffected	semver	—
`[7.2.8,7.3.0)`	unaffected	semver	—
`[7.3-rc4,*]`	unaffected	generic	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Apply the vendor‑supplied kernel patch that validates access flags before reassigning the memory region’s protection domain.
Upgrade to the latest stable Linux kernel version that includes the rxe driver fix.
If an immediate kernel upgrade is not possible, disable the RDMA/rxe driver or restrict RDMA user access by revoking CAP_SYS_ADMIN rights to the relevant processes.

Generated by OpenCVE AI on October 9, 2026 at 05:25 UTC.

Tracking

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Advisories

Source	ID	Title
Debian DLA	DLA-4850-1	linux-6.12 security update
Debian DSA	DSA-6568-1	linux security update

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.

The EPSS score is 0.00116.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98366.mbox
https://git.kernel.org/stable/c/08f12745cb72981aa2cabe214af0c7a42a856f0a
https://git.kernel.org/stable/c/4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8
https://git.kernel.org/stable/c/7230cc456d4bb2221c20c5f1d22b38b8576aa16f
https://git.kernel.org/stable/c/ae36a5b609ae79f4de966328b78d2584be9719a4
https://git.kernel.org/stable/c/fe602c91a52e161ace4afd5bdb8f33270c554c6f
https://nvd.nist.gov/vuln/detail/CVE-2026-98366
https://www.cve.org/CVERecord?id=CVE-2026-98366

History

Fri, 09 Oct 2026 04:30:00 +0000

Type	Values Removed	Values Added
Weaknesses	CWE-416

Fri, 09 Oct 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-825
References		https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98366.mbox https://nvd.nist.gov/vuln/detail/CVE-2026-98366 https://www.cve.org/CVERecord?id=CVE-2026-98366
Metrics	threat_severity `None`	threat_severity `Moderate`

Wed, 07 Oct 2026 07:00:00 +0000

Type	Values Removed	Values Added
Metrics		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'}`

Tue, 06 Oct 2026 13:45:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-416

Tue, 06 Oct 2026 09:00:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: validate access flags before swapping the MR's PD rxe_rereg_user_mr() reassigns mr->ibmr.pd first and only then validates the IB_MR_REREG_ACCESS argument: if (flags & IB_MR_REREG_PD) { rxe_put(old_pd); rxe_get(pd); mr->ibmr.pd = ibpd; } if (flags & IB_MR_REREG_ACCESS) { if (access & ~RXE_ACCESS_SUPPORTED_MR) return ERR_PTR(-EOPNOTSUPP); mr->access = access; } Both flags pass the entry check because RXE_MR_REREG_SUPPORTED is IB_MR_REREG_PD \| IB_MR_REREG_ACCESS, so a caller can reach the access check with mr->ibmr.pd already reassigned. mr->ibmr.pd is owned by the core, which adjusts pd->usecnt only on the success path: ib_uverbs_rereg_mr() jumps to put_new_uobj on a driver error without undoing the reassignment, so mr->pd == new_pd while the usecnts still charge the MR to orig_pd. ib_dereg_mr_user() then decrements new_pd, whose count can reach zero while a memory window still references it; uverbs_free_pd() frees the PD on that count alone and rxe_mw_cleanup() writes to freed memory: BUG: KASAN: slab-use-after-free in __rxe_put+0x31/0xa0 Write of size 4 at addr ffff8881301dd690 by task rxe_poc/591 __rxe_put+0x31/0xa0 rxe_mw_cleanup+0x42/0x200 __rxe_cleanup+0x115/0x370 rxe_dealloc_mw+0x4c/0x80 Allocated by task 591: ib_uverbs_alloc_pd+0x258/0x540 Freed by task 591: ib_dealloc_pd_user+0x174/0x210 uverbs_free_pd+0x8d/0xc0 ib_uverbs_dealloc_pd+0x18e/0x1d0 Validate the access flags before mutating any state so the callback either applies every requested change or none.
Title		RDMA/rxe: validate access flags before swapping the MR's PD
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/08f12745cb72981aa2cabe214af0c7a42a856f0a https://git.kernel.org/stable/c/4dd7a53f1c5b44693c26dac4b9b5bd5bb9d604c8 https://git.kernel.org/stable/c/7230cc456d4bb2221c20c5f1d22b38b8576aa16f https://git.kernel.org/stable/c/ae36a5b609ae79f4de966328b78d2584be9719a4 https://git.kernel.org/stable/c/fe602c91a52e161ace4afd5bdb8f33270c554c6f

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Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-10-06T08:46:51.638Z

Updated: 2026-10-19T09:18:18.297Z

Reserved: 2026-09-25T10:25:14.344Z

Link: CVE-2026-98366

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-10-06T09:18:30.823

Modified: 2026-10-19T10:18:39.543

Link: CVE-2026-98366

Redhat

Severity : Moderate

Publid Date: 2026-10-06T00:00:00Z

Links: CVE-2026-98366 - Bugzilla

OpenCVE Enrichment

Updated: 2026-10-09T05:30:08Z

Weaknesses

CWE-825
Expired Pointer Dereference

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

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