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Linux Kernel CVE-2026-46181

| EUVDEUVD-2026-32808 HIGH
Race Condition within a Thread (CWE-366)
2026-05-28 416baaa9-dc9f-4396-8d5f-8c081fb06d67 GHSA-pw2f-xmgc-f22m
Denial Of Service Linux
7.8
CVSS 3.1 · Vendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain local shell with RDMA device access
  2. Delivery
    Open mlx4 uverbs device
  3. Exploit
    Race SRQ create/destroy against async events
  4. Execution
    Trigger use-after-free in mlx4_srq_event()
  5. Persist
    Corrupt kernel memory or crash host
  6. Impact
    Escalate to root or deny service

Vulnerability Assessment

Weakness
CWE
CWE-366
ASVS 5.0
V15 - Secure Coding and Architecture Shared resource synchronization
Exploitation Conditions

The target system must have a Mellanox ConnectX-class HCA present and the mlx4_ib kernel module loaded, the attacker must hold local low-privilege shell access (PR:L) with permission to open /dev/infiniband/uverbs* (typically requires membership in the rdma group or equivalent), and must be able to issue ibv_create_srq()/ibv_destroy_srq() verbs to win a narrow race window against asynchronous SRQ event delivery from the HCA firmware. Exploitation is limited by AV:L (no network reachability), the requirement that RDMA hardware actually exist on the host (excluding cloud VMs without SR-IOV RDMA, laptops, and general-purpose servers), and the tight timing window that requires repeated attempts; no user interaction is required (UI:N).
Impact

The CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H vector indicates a local attacker with low privileges can achieve high impact across all three triad properties, but realistic risk is substantially constrained. EPSS at 0.02% (4th percentile) and no CISA KEV listing align with the lack of any public PoC, making opportunistic exploitation unlikely. Exploitation also requires the target host to have Mellanox ConnectX mlx4-class RDMA hardware physically present and the driver loaded - a configuration mostly seen in HPC clusters, storage fabrics, and some hyperscaler hosts, not general-purpose servers or endpoints. The CWE field is N/A in the input, but the root cause class is clearly CWE-416 (use-after-free) combined with CWE-362 (race condition) based on the patch description. Tags labeling this 'Denial of Service' likely understate impact: a race-induced UAF in kernel context could in principle be escalated to code execution, though the C:H/I:H rating is uncorroborated by any published exploitation research.
Exploit ScenarioDerived

A local low-privileged user on an HPC compute node equipped with a Mellanox ConnectX-3 HCA opens an RDMA verbs device, races SRQ creation against asynchronous event delivery by repeatedly creating and destroying shared receive queues while triggering events, and hits the window where mlx4_srq_event() dereferences a partially initialized or already-freed mlx4_srq object. The resulting use-after-free in kernel context can crash the node (denial of service of the entire host) or, with skilled heap grooming, be steered toward privilege escalation to root. No public exploit identified at time of analysis.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – May 30, 2026

Local privilege escalation or denial-of-service in the Linux kernel's RDMA/mlx4 InfiniBand driver stems from improper RCU synchronization in mlx4_srq_event(), where the mlx4_srq structure is never freed via RCU and can be accessed before initialization completes. Local low-privileged users on systems using Mellanox ConnectX (mlx4) RDMA hardware can trigger a race condition leading to memory corruption or kernel crash, with CVSS 7.8 reflecting high confidentiality, integrity, and availability impact. There is no public exploit identified at time of analysis, and EPSS scores this at just 0.02%, indicating minimal real-world exploitation likelihood.

RemediationAI

Vendor-released patch: upgrade to Linux 6.18.30, 7.0.7, 7.1-rc3 or later as listed in the EUVD record, applying the upstream commits 1e2a44875b6a, 8b7833f3bce3, and c9341307ea16 from git.kernel.org/stable. Distribution users should pull the corresponding stable-tree update from their vendor (RHEL, SUSE, Ubuntu, Debian, Oracle Linux) once published; consult https://nvd.nist.gov/vuln/detail/CVE-2026-46181 for cross-references. As a compensating control on systems that cannot reboot immediately, unload the mlx4_ib module (modprobe -r mlx4_ib) or blacklist it if RDMA is unused - the trade-off is loss of InfiniBand/RoCE functionality on Mellanox ConnectX-3 hardware, breaking RDMA-based storage (NFS-RDMA, iSER), MPI workloads, and any application using libibverbs against mlx4. Where the driver must remain loaded, restrict local shell access and RDMA verbs device access (/dev/infiniband/*) to trusted users only, since exploitation requires local code execution privileges.

Affected VersionsENISA

Linux patch: 7.0.7
Linux 30353bfc43a1602c020f31d95cf27182ffd23824 <c9341307ea16b9395c2e4c9c94d8499d91fe31d0
Linux patch: 0
Linux patch: 7.1-rc3
Linux 4.9
Linux patch: 6.18.30
Linux 30353bfc43a1602c020f31d95cf27182ffd23824 <8b7833f3bce35cb0d01c1503781523c099c675f0
Linux 30353bfc43a1602c020f31d95cf27182ffd23824 <1e2a44875b6afb4add1115f7f3351dcbeb6f273d

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Technical ContextAI · show details

The flaw resides in the mlx4 InfiniBand/RDMA driver (drivers/infiniband/hw/mlx4) which supports Mellanox ConnectX-3 and earlier HCAs, specifically in the Shared Receive Queue (SRQ) event handler mlx4_srq_event(). The original code used RCU (Read-Copy-Update) to protect lookups in a radix_tree, but while the radix_tree itself is RCU-safe, the mlx4_srq objects it indexes are freed using normal kfree() rather than call_rcu()/kfree_rcu(), and the event handler does not actually execute inside an rcu_read_lock() critical section. This creates a classic use-after-free / time-of-check-to-time-of-use race when an asynchronous SRQ event is delivered while the object is being torn down or before refcount_set() finalizes initialization. The fix replaces the unsound RCU pattern with the SRQ spinlock plus refcount_inc_not_zero() to safely reject partially constructed objects, and reorders refcount_set() to occur only after full initialization.

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Severity by source

Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SUSE HIGH
Red Hat 7.0 HIGH

Primary rating from Vendor (416baaa9-dc9f-4396-8d5f-8c081fb06d67).

CVSS VectorVendor: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

4
CVSS changed
May 30, 2026 - 11:22 NVD
7.8 (HIGH)
Patch available
May 28, 2026 - 12:01 EUVD
CVE Published
May 28, 2026 - 10:16 nvd
UNKNOWN (no severity yet)
CVE Published
May 28, 2026 - 10:16 nvd
HIGH 7.8

DescriptionCVE.org

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.

Executive ViewAI

Why It Matters

A local privilege escalation vulnerability in the Linux kernel's Mellanox RDMA driver (CVE-2026-46181, CVSS 7.8) allows unprivileged system users to gain administrative access or crash servers on infrastructure using ConnectX hardware. Organizations operating high-performance computing clusters, data centers, or other environments dependent on RDMA acceleration face potential compromise of access controls, system stability, and operational continuity. While real-world exploitation is assessed as minimal (EPSS 0.02%), successful attacks could extend to data confidentiality and integrity across interconnected infrastructure.

Business Impact: Medium
Compensating Controls

Apply vendor patch. If patching cannot be immediately deployed, restrict local system access to trusted users only, disable the mlx4_ib kernel module if RDMA functionality is not required for operations, and enable detailed audit logging for privilege escalation events.

Threat Intelligence Overview

EPSS Score
0.0%
Top 96% exploitable
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS MSRC Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact
Medium

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Same weakness CWE-366 – Race Condition within a Thread

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4.4
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Same technique Denial Of Service

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CVE-2015-5119 CRITICAL POC
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CVE-2011-2462 CRITICAL POC
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CVE-2011-0611 HIGH POC
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CVE-2012-1889 HIGH POC
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CVE-2012-0507 CRITICAL POC
9.8
CVE-2014-1761 HIGH POC
7.8
CVE-2015-5122 CRITICAL POC
9.8
CVE-2011-0609 HIGH POC
7.8

Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7 Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-46181 ADVISORY https://ubuntu.com/security/notices/USN-8566-1 ADVISORY https://ubuntu.com/security/notices/USN-8568-1 ADVISORY https://vuldb.com/vuln/366694 REF https://access.redhat.com/errata/RHSA-2026:25120 REF https://access.redhat.com/errata/RHSA-2026:25121 REF https://access.redhat.com/errata/RHSA-2026:25217 REF https://access.redhat.com/errata/RHSA-2026:33900 REF https://access.redhat.com/errata/RHSA-2026:34094 REF https://access.redhat.com/errata/RHSA-2026:34095 REF https://access.redhat.com/errata/RHSA-2026:34443 REF https://access.redhat.com/errata/RHSA-2026:35863 REF https://access.redhat.com/errata/RHSA-2026:35894 REF https://access.redhat.com/errata/RHSA-2026:35896 REF https://access.redhat.com/errata/RHSA-2026:36216 REF https://access.redhat.com/errata/RHSA-2026:41236 REF https://access.redhat.com/security/cve/CVE-2026-46181 REF https://bugzilla.redhat.com/show_bug.cgi?id=2482532 REF https://git.kernel.org/stable/c/1e2a44875b6afb4add1115f7f3351dcbeb6f273d REF https://git.kernel.org/stable/c/2d8b30b496bc53e961ba7415fd629fc27813017c REF https://git.kernel.org/stable/c/8b7833f3bce35cb0d01c1503781523c099c675f0 REF https://git.kernel.org/stable/c/c9341307ea16b9395c2e4c9c94d8499d91fe31d0 REF https://git.kernel.org/stable/c/f0dbd9355ce1e93808541260c7ffab7956df9233 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46181.json

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