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

smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available

The logic off managing recv credits by counting posted recv_io and
granted credits is racy.

That's because the peer might already consumed a credit,
but between receiving the incoming recv at the hardware
and processing the completion in the 'recv_done' functions
we likely have a window where we grant credits, which
don't really exist.

So we better have a decicated counter for the
available credits, which will be incremented
when we posted new recv buffers and drained when
we grant the credits to the peer.
Published: 2026-04-24
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service via SMB Direct credit race
Action: Patch Kernel
AI Analysis

Impact

The flaw is a race condition in the Linux kernel’s SMB Direct implementation, where the module mishandles the tracking of receive credits. It may grant credits that have already been consumed by a peer, potentially leading to resource exhaustion or incorrect data handling. The weakness is classified as a race condition (CWE‑821).

Affected Systems

All Linux kernels that ship SMB Direct support, across all distributions, are potentially affected. No specific version range is listed, so any kernel lacking the fix commits remains vulnerable.

Risk and Exploitability

With a CVSS score of 7.5 the vulnerability is considered high severity, however the EPSS score of less than 1 % indicates a low probability of exploitation. It is not currently listed in the CISA KEV catalog. An attacker would need to interact with the SMB Direct protocol on a target system, likely from the network, to exploit the race window and stress the connection or cause a denial of service.

Generated by OpenCVE AI on April 29, 2026 at 01:42 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update to a Linux kernel release that includes the SMB Direct receive‑credit fix (e.g., apply the patch containing the commit that introduces smbdirect_socket.recv_io.credits.available counter).
  • If an immediate kernel upgrade is not possible, recompile the kernel with SMB Direct support disabled (CONFIG_SMB_DIRECT=y disabled) or set any available kernel boot parameters that limit SMB Direct operation until the patch is applied.
  • Monitor SMB traffic for abnormal credit or error patterns, and apply network segmentation or firewall rules to restrict SMB Direct traffic to trusted hosts as an interim protective measure.

Generated by OpenCVE AI on April 29, 2026 at 01:42 UTC.

Tracking

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Advisories

No advisories yet.

History

Tue, 28 Apr 2026 19:00:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo

Mon, 27 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Sat, 25 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-821
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate


Fri, 24 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available The logic off managing recv credits by counting posted recv_io and granted credits is racy. That's because the peer might already consumed a credit, but between receiving the incoming recv at the hardware and processing the completion in the 'recv_done' functions we likely have a window where we grant credits, which don't really exist. So we better have a decicated counter for the available credits, which will be incremented when we posted new recv buffers and drained when we grant the credits to the peer.
Title smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T22:10:44.030Z

Reserved: 2026-03-09T15:48:24.114Z

Link: CVE-2026-31539

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-04-24T15:16:27.843

Modified: 2026-04-28T18:54:11.557

Link: CVE-2026-31539

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-24T00:00:00Z

Links: CVE-2026-31539 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-29T01:45:26Z

Weaknesses