CVE-2026-93267

RDMA/core: Fix potential use after free in uverbs_free_dmah()

Published Sep 24, 2026 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

RDMA/core: Fix potential use after free in uverbs_free_dmah()

When accessing a dmah via the netlink path the only synchronization
mechanism for the said dmah is rdma_restrack_get().
Currently, rdma_restrack_del() is invoked at the end of
uverbs_free_dmah(), which is too late, since by that point
vendor-specific resources associated with the dmah might already be
freed. This can leave a short window where the dmah remains accessible
through restrack, leading to a potential use-after-free.

Fix this by moving the rdma_restrack_begin_del() call to the start of
uverbs_free_dmah(), ensuring that the dmah is removed from restrack
before its internal resources are released. This guarantees that no new
users hold references to a dmah that is in the process of destruction.

In addition, this change preserves the intended inverted order
between create and destroy routines: resources are added to
restrack at the end of successful creation, and hence shall be removed
from the restrack first thing during the destruction flow, which keeps
the lifecycle management consistent and predictable.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-9019-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9020-1 Linux kernel vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-416
Type Values Removed Values Added
Weaknesses CWE-825
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-416
Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: RDMA/core: Fix potential use after free in uverbs_free_dmah() When accessing a dmah via the netlink path the only synchronization mechanism for the said dmah is rdma_restrack_get(). Currently, rdma_restrack_del() is invoked at the end of uverbs_free_dmah(), which is too late, since by that point vendor-specific resources associated with the dmah might already be freed. This can leave a short window where the dmah remains accessible through restrack, leading to a potential use-after-free. Fix this by moving the rdma_restrack_begin_del() call to the start of uverbs_free_dmah(), ensuring that the dmah is removed from restrack before its internal resources are released. This guarantees that no new users hold references to a dmah that is in the process of destruction. In addition, this change preserves the intended inverted order between create and destroy routines: resources are added to restrack at the end of successful creation, and hence shall be removed from the restrack first thing during the destruction flow, which keeps the lifecycle management consistent and predictable.
Title RDMA/core: Fix potential use after free in uverbs_free_dmah()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 19, 2026, 9:08 AM
Reserved
Sep 17, 2026, 4:02 PM
Status
Received
Published
Sep 24, 2026, 4:17 PM
Modified
Oct 19, 2026, 10:17 AM
Severity
Moderate
Public date
Sep 24, 2026, 12:00 AM