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CVE Record

CVE-2026-46181: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event()

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event() Sashiko points out the radix_tree itself is RCU safe, but nothing ever frees the mlx4_srq struct with RCU, and it isn't even accessed within the RCU critical section. It also will crash if an event is delivered before the srq object is finished initializing. Use the spinlock since it isn't easy to make RCU work, use refcount_inc_not_zero() to protect against partially initialized objects, and order the refcount_set() to be after the srq is fully initialized.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-46181 is a Linux kernel race-condition bug in the RDMA mlx4 driver. A local user with some privileges could potentially crash the system or impact confidentiality and integrity. It matters most for Linux hosts using Mellanox mlx4/RDMA capabilities. No active exploitation is stated in the provided sources.

Executive priority

Prioritize patching for Linux servers using Mellanox mlx4/RDMA, especially shared compute, HPC, virtualization, or multi-user environments. Treat as high severity, but not an internet-wide emergency based on current sources.

Technical view

The issue is in RDMA/mlx4 mlx4_srq_event(). The kernel fix replaces improper RCU assumptions with spinlock/refcount handling and orders refcount initialization after SRQ initialization. The CVSS 3.1 score is 7.8, local attack vector, low complexity, low privileges, no user interaction, with high confidentiality, integrity, and availability impact.

Likely exposure

Exposure is likely limited to affected Linux kernels where the RDMA mlx4 driver and SRQ event path are present or usable. Systems without mlx4/RDMA hardware or driver use are less likely exposed, but confirm through vendor kernel advisories and configuration review.

Exploitation context

The CVSS vector indicates local, low-privilege exploitation with no user interaction. The sources do not state remote exploitation or known active exploitation. The bug involves a race during SRQ event handling and object initialization/lifetime management.

Researcher notes

Affected-version data in the source bundle is inconsistent and should be validated against distribution advisories. The core fix addresses unsafe lifetime handling around radix tree lookup, SRQ initialization, and refcounting in mlx4_srq_event(). No exploit proof or KEV listing is provided.

Mitigation direction

  • Apply vendor kernel updates that include the referenced stable Linux fixes.
  • For Red Hat systems, review the listed RHSA errata for applicable packages.
  • If mlx4/RDMA is unnecessary, evaluate vendor-supported ways to reduce or disable exposure.
  • Track vendor advisories for corrected affected-version ranges and backports.

Validation and detection

  • Inventory Linux kernel versions across RDMA-capable systems.
  • Identify hosts using mlx4 or Mellanox RDMA functionality.
  • Compare installed kernels against vendor advisories and RHSA errata.
  • Confirm the referenced stable commits are included in your deployed kernel build.
  • Document systems without mlx4/RDMA as lower-priority after verification.
Prepared
Confidence
medium
Sources
12

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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CWE-366: Exact CWE lookup

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CVE-2026-46181 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.

2CVSS vectors
5Timeline events
1ADP providers
18Source links

CVSS vector scores

2 official scores

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
7CVSS 3.1HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H15.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-46181Attack 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. ADP timelineredhat-SADP

    Reported to Red Hat.

  3. ADP timelineredhat-SADP

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

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

ADP provider summaries

redhat-SADPkernel: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event()
other:Red Hat severity ratingcvssV3_1
  • 2026-05-28T00:00:00.000Z: Reported to Red Hat.
  • 2026-05-28T00:00:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux30353bfc43a1602c020f31d95cf27182ffd23824, 30353bfc43a1602c020f31d95cf27182ffd23824, 30353bfc43a1602c020f31d95cf27182ffd23824unaffected
LinuxLinux4.9, 0, 6.18.30, 7.0.7, 7.1affected
Weakness

CWE details

CWE-366

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CWE-366 · source CWE mapping

Race Condition within a Thread

Race Condition within a Thread represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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