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Linux Kernel EUVDEUVD-2026-39272

| CVE-2026-53181 MEDIUM
Memory Leak (CWE-401)
2026-06-25 416baaa9-dc9f-4396-8d5f-8c081fb06d67 GHSA-6gq6-hxjh-9grq
Denial Of Service Linux Red Hat Suse
5.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.5 MEDIUM

Requires local low-privilege access to initiate vsock connections; impact is availability-only (permanent listener DoS), with no confidentiality or integrity consequences.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
7.0 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

5
Analysis Generated
Jul 06, 2026 - 12:53 vuln.today
CVSS changed
Jul 06, 2026 - 12:52 NVD
5.5 (MEDIUM)
Patch available
Jun 25, 2026 - 10:32 EUVD
CVE Published
Jun 25, 2026 - 09:16 nvd
MEDIUM 5.5
CVE Published
Jun 25, 2026 - 09:16 cve.org
UNKNOWN (no severity yet)

DescriptionNVD

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

vsock/vmci: fix sk_ack_backlog leak on failed handshake

When vmci_transport_recv_connecting_server() returns an error, vmci_transport_recv_listen() calls vsock_remove_pending() but never calls sk_acceptq_removed(). This leaves sk_ack_backlog incremented permanently.

Repeated handshake failures (malformed packets, queue pair alloc failure, event subscribe failure) cause sk_ack_backlog to climb toward sk_max_ack_backlog. Once it reaches the limit the listener permanently refuses all new connections with -ECONNREFUSED, a silent denial of service requiring a process restart to recover.

The two existing sk_acceptq_removed() calls in af_vsock.c do not cover this path: line 764 checks vsock_is_pending() which returns false after vsock_remove_pending(), and line 1889 is only reached on successful accept().

Fix by balancing sk_acceptq_added() with sk_acceptq_removed() on the error path.

AnalysisAI

The vsock/VMCI transport in the Linux kernel silently leaks the accept queue counter (sk_ack_backlog) on every failed vsock connection handshake, eventually causing a permanent denial of service on any vsock listener. Repeated handshake failures caused by malformed packets, queue pair allocation failures, or event subscription failures each increment sk_ack_backlog without a corresponding decrement; once the counter reaches sk_max_ack_backlog, the listener rejects all subsequent connections with -ECONNREFUSED until the owning process is restarted. No public exploit identified at time of analysis; EPSS of 0.18% at the 8th percentile reflects low automated exploitation probability, consistent with the VMware-specific exposure requirement.

Technical ContextAI

The vulnerability is in the vsock subsystem's VMCI (Virtual Machine Communication Interface) transport layer, specifically in vmci_transport_recv_listen() and vmci_transport_recv_connecting_server() in the Linux kernel source. VMCI is a VMware-proprietary transport for AF_VSOCK sockets enabling communication between guest VMs and the hypervisor or between guests. CWE-401 (Missing Release of Memory after Effective Lifetime) applies here as a counter lifecycle imbalance: sk_acceptq_added() is called when a connection is placed in the pending queue, but when vmci_transport_recv_connecting_server() returns an error, vmci_transport_recv_listen() calls vsock_remove_pending() without calling sk_acceptq_removed(). The two existing sk_acceptq_removed() call sites in af_vsock.c do not cover this path: the check at line 764 queries vsock_is_pending() which returns false after vsock_remove_pending() has already run, and the call at line 1889 is only reached on a successful accept(). The fix balances the counter on the error path. Affected CPE: cpe:2.3:o:linux:linux_kernel across multiple stable branches from 3.9 through 7.1-rc3.

RemediationAI

Upgrade to a patched kernel version appropriate for your distribution's LTS branch: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 7.0.13, or 7.1 stable. Upstream patch commits are available at https://git.kernel.org/stable/c/22c587aa3ab1ab5264daff3ec32136fd30436c13 and parallel stable-branch commits at https://git.kernel.org/stable/c/9698582a4dd9c4a05889d7db96d4c0edc9e69cac, https://git.kernel.org/stable/c/ba9ad6015937a5e46ba1a31370e3efdec8abbdcc, and others referenced in the NVD entry. As an interim workaround where vsock/VMCI is not required, unload the vmci_transport module (modprobe -r vmci_transport), though this will break VMware Tools communication and any dependent inter-VM services-assess this trade-off before applying in production. If the DoS has already been triggered, restarting the affected vsock-listening process restores connectivity without requiring a system reboot. Restricting guest VM access to vsock endpoints at the hypervisor level reduces the attack surface in multi-tenant VMware environments.

Same weakness CWE-401 – Memory Leak

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.177 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.155 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.206 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.152 Affected
Image SLES15-SP7-Azure-3P Image SLES15-SP7-Azure-Basic Image SLES15-SP7-Azure-Standard Image SLES15-SP7-HPC-Azure Affected
Image SLES15-SP7-BYOS-Azure Image SLES15-SP7-BYOS-GCE Image SLES15-SP7-CHOST-BYOS-Aliyun Image SLES15-SP7-CHOST-BYOS-Azure Image SLES15-SP7-CHOST-BYOS-EC2 Image SLES15-SP7-CHOST-BYOS-GCE Image SLES15-SP7-CHOST-BYOS-GDC Image SLES15-SP7-CHOST-BYOS-SAP-CCloud Image SLES15-SP7-EC2 Image SLES15-SP7-EC2-ECS-HVM Image SLES15-SP7-GCE Image SLES15-SP7-HPC-BYOS-Azure Image SLES15-SP7-HPC-BYOS-EC2 Image SLES15-SP7-HPC-BYOS-GCE Image SLES15-SP7-Hardened-BYOS-Azure Image SLES15-SP7-Hardened-BYOS-EC2 Image SLES15-SP7-Hardened-BYOS-GCE Image SLES15-SP7-SAPCAL-Azure Image SLES15-SP7-SAPCAL-EC2 Image SLES15-SP7-SAPCAL-GCE Affected
Image SLES15-SP7-SAP-Azure Image SLES15-SP7-SAP-Azure-3P Image SLES15-SP7-SAP-BYOS-Azure Image SLES15-SP7-SAP-BYOS-EC2 Image SLES15-SP7-SAP-BYOS-GCE Image SLES15-SP7-SAP-EC2 Image SLES15-SP7-SAP-GCE Image SLES15-SP7-SAP-Hardened-Azure Image SLES15-SP7-SAP-Hardened-BYOS-Azure Image SLES15-SP7-SAP-Hardened-BYOS-EC2 Image SLES15-SP7-SAP-Hardened-BYOS-GCE Image SLES15-SP7-SAP-Hardened-GCE Affected

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EUVD-2026-39272 vulnerability details – vuln.today
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