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CVE Record

CVE-2026-43128: RDMA/umem: Fix double dma_buf_unpin in failure path

In the Linux kernel, the following vulnerability has been resolved: RDMA/umem: Fix double dma_buf_unpin in failure path In ib_umem_dmabuf_get_pinned_with_dma_device(), the call to ib_umem_dmabuf_map_pages() can fail. If this occurs, the dmabuf is immediately unpinned but the umem_dmabuf->pinned flag is still set. Then, when ib_umem_release() is called, it calls ib_umem_dmabuf_revoke() which will call dma_buf_unpin() again. Fix this by removing the immediate unpin upon failure and just let the ib_umem_release/revoke path handle it. This also ensures the proper unmap-unpin unwind ordering if the dmabuf_map_pages call happened to fail due to dma_resv_wait_timeout (and therefore has a non-NULL umem_dmabuf->sgt).

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel error can release the same DMA buffer twice when an RDMA memory-mapping operation fails. This may destabilize the kernel or permit broader security impact for a local, low-privileged user able to reach the affected path. The supplied CVSS score is 7.8 (High).

Executive priority

Treat as a high-priority kernel update for exposed RDMA-capable systems, especially shared or multi-user infrastructure. Broad emergency action is not supported by the supplied evidence because exploitation is local and active exploitation is unconfirmed. Establish actual reachability and vendor patch status promptly.

Technical view

In ib_umem_dmabuf_get_pinned_with_dma_device(), a failed ib_umem_dmabuf_map_pages() unpins a DMA-BUF without clearing its pinned flag. Later, ib_umem_release() invokes the revoke path and unpins it again. The correction leaves unpinning to release/revoke, preserving proper unmap-before-unpin ordering.

Likely exposure

Exposure is most likely on listed affected Linux kernels where local users or workloads can reach the RDMA/umem DMA-BUF mapping path. Exact distribution packages, configurations, hardware requirements, and backport status are not provided, so version strings alone may not determine exposure.

Exploitation context

The CVSS vector indicates local access, low attack complexity, low privileges, and no user interaction, with potentially high confidentiality, integrity, and availability impact. The bundle reports no CISA KEV listing and provides no evidence of active exploitation or a public exploit.

Researcher notes

The vulnerable condition occurs on the map-pages failure path while pinned remains true. Release then reaches revoke and performs the second dma_buf_unpin(). The fix removes the immediate failure-path unpin and also addresses unwind ordering when a non-NULL scatter-gather table remains after dma_resv_wait_timeout failure.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable upstream stable correction.
  • Check distribution security guidance for package versions and backport status.
  • Prioritize RDMA-capable multi-user or shared-compute hosts.
  • Restrict untrusted local access to exposed systems until remediation is confirmed.

Validation and detection

  • Inventory running kernel versions on systems using RDMA or DMA-BUF integrations.
  • Compare installed packages with distribution advisories and backport records.
  • Verify the applicable stable correction is present in the kernel source or package changelog.
  • After updating, confirm the fixed kernel is running and RDMA workloads operate normally.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-43128 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
7Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-43128Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1e4df4a21c5ac722df1099eee30cad9246c889b5, 1e4df4a21c5ac722df1099eee30cad9246c889b5, 1e4df4a21c5ac722df1099eee30cad9246c889b5, 1e4df4a21c5ac722df1099eee30cad9246c889b5, 1e4df4a21c5ac722df1099eee30cad9246c889b5, 1e4df4a21c5ac722df1099eee30cad9246c889b5unaffected
LinuxLinux5.16, 0, 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0affected
Weakness

CWE details

No CWE listed

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