CVE-2025-39929

Memory exhaustion via leaked SMB Direct receive buffer

Published Oct 4, 2025 · Updated Oct 4, 2025

Memory leak in the SMB Direct client in affected Linux kernel releases allows local users to exhaust kernel memory during negotiation. The smbd_negotiate() error path returns when smbd_post_recv() fails without calling put_receive_buffer() for the allocated response. Local access sufficient to initiate SMB Direct negotiation is required; repeated failures retain receive objects and can deplete memory, causing a service interrupt.

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

Memory leak in the SMB Direct client in affected Linux kernel releases allows local users to exhaust kernel memory during negotiation. The smbd_negotiate() error path returns when smbd_post_recv() fails without calling put_receive_buffer() for the allocated response. Local access sufficient to initiate SMB Direct negotiation is required; repeated failures retain receive objects and can deplete memory, causing a service interrupt.

The record

CVE
CVE-2025-39929
Published
Oct 4, 2025
Updated
Oct 4, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 4, 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=4.16
  2. Affected versionversion=f198186aa9bbd60fae7a2061f4feec614d880299 <0991418bf98f191d0c320bd25245fcffa1998c7e
  3. Affected versionversion=f198186aa9bbd60fae7a2061f4feec614d880299 <3d7c075c878ac844e33c43e506c2fa27ac7e9689
  4. Affected versionversion=f198186aa9bbd60fae7a2061f4feec614d880299 <922338efaad63cfe30d459dfc59f9d69ff93ded4
  5. Affected versionversion=f198186aa9bbd60fae7a2061f4feec614d880299 <daac51c7032036a0ca5f1aa419ad1b0471d1c6e0
  6. Affected versionversion=f198186aa9bbd60fae7a2061f4feec614d880299 <e7b7a93879558e77d950f1ff9a6f3daa385b33df

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.16; version=f198186aa9bbd60fae7a2061f4feec614d880299 <0991418bf98f191d0c320bd25245fcffa1998c7e; version=f198186aa9bbd60fae7a2061f4feec614d880299 <3d7c075c878ac844e33c43e506c2fa27ac7e9689; version=f198186aa9bbd60fae7a2061f4feec614d880299 <922338efaad63cfe30d459dfc59f9d69ff93ded4; version=f198186aa9bbd60fae7a2061f4feec614d880299 <daac51c7032036a0ca5f1aa419ad1b0471d1c6e0; version=f198186aa9bbd60fae7a2061f4feec614d880299 <e7b7a93879558e77d950f1ff9a6f3daa385b33df

Published CVSS scores

5.5NIST NVDCVSS: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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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