CVE-2025-39857Network attack vector

Unauthenticated service hang via unchecked DMA device

Published Sep 19, 2025 · Updated Sep 19, 2025

A NULL pointer dereference in the Linux kernel SMC subsystem allows remote attackers to hang subsequent SMC connections via a CLC proposal. smc_ib_is_sg_need_sync() dereferences ibdev->dma_device without checking for NULL while mapping an SMC-R buffer on software RoCE devices. An SMC-enabled listening socket backed by rxe or siw is required; the resulting oops can permanently deadlock SMC or panic the host when panic_on_oops is enabled.

CVSS severity5.5
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A NULL pointer dereference in the Linux kernel SMC subsystem allows remote attackers to hang subsequent SMC connections via a CLC proposal. smc_ib_is_sg_need_sync() dereferences ibdev->dma_device without checking for NULL while mapping an SMC-R buffer on software RoCE devices. An SMC-enabled listening socket backed by rxe or siw is required; the resulting oops can permanently deadlock SMC or panic the host when panic_on_oops is enabled.

The record

CVE
CVE-2025-39857
Published
Sep 19, 2025
Updated
Sep 19, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0ef69e788411cba2af017db731a9fc62d255e9ac <0cdf1fd8fc59d44a48c694324611136910301ef9
  2. Affected versionversion=0ef69e788411cba2af017db731a9fc62d255e9ac <34f17cbe027050b8d5316ea1b6f9bd7c378e92de
  3. Affected versionversion=0ef69e788411cba2af017db731a9fc62d255e9ac <ba1e9421cf1a8369d25c3832439702a015d6b5f9
  4. Affected versionversion=0ef69e788411cba2af017db731a9fc62d255e9ac <eb929910bd4b4165920fa06a87b22cc6cae92e0e
  5. Affected versionversion=0ef69e788411cba2af017db731a9fc62d255e9ac <f18d9b3abf9c6587372cc702f963a7592277ed56
  6. Affected versionversion=6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0ef69e788411cba2af017db731a9fc62d255e9ac <0cdf1fd8fc59d44a48c694324611136910301ef9; version=0ef69e788411cba2af017db731a9fc62d255e9ac <34f17cbe027050b8d5316ea1b6f9bd7c378e92de; version=0ef69e788411cba2af017db731a9fc62d255e9ac <ba1e9421cf1a8369d25c3832439702a015d6b5f9; version=0ef69e788411cba2af017db731a9fc62d255e9ac <eb929910bd4b4165920fa06a87b22cc6cae92e0e; version=0ef69e788411cba2af017db731a9fc62d255e9ac <f18d9b3abf9c6587372cc702f963a7592277ed56; version=6.0

Published CVSS scores

5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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