CVE-2025-39819

Denial of service via leaked SMB file reference

Published Sep 16, 2025 · Updated Sep 16, 2025

Resource leak in the Linux kernel SMB client allows local users to interrupt service by exhausting resources during SMB2 compound operations. In smb2_compound_op, the ENOMEM branch after vars allocation fails returns without dropping the cfile reference required by the function's cleanup contract. Repeated reachability requires low-privileged local access and allocation failures; the resulting reference leak can consume resources until service is unavailable.

CVSS severity6.8
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource leak in the Linux kernel SMB client allows local users to interrupt service by exhausting resources during SMB2 compound operations. In smb2_compound_op, the ENOMEM branch after vars allocation fails returns without dropping the cfile reference required by the function's cleanup contract. Repeated reachability requires low-privileged local access and allocation failures; the resulting reference leak can consume resources until service is unavailable.

The record

CVE
CVE-2025-39819
Published
Sep 16, 2025
Updated
Sep 16, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3fc11ff13fbc2749871d6ac2141685cf54699997
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4191ea1f0bb3e27d65c5dcde7bd00e709ec67141
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4735f5991f51468b85affb8366b7067248457a71
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ab529e6ca1f67bcf31f3ea80c72bffde2e9e053e
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cc82c6dff548f0066a51a6e577c7454e7d26a968

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3fc11ff13fbc2749871d6ac2141685cf54699997; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4191ea1f0bb3e27d65c5dcde7bd00e709ec67141; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4735f5991f51468b85affb8366b7067248457a71; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ab529e6ca1f67bcf31f3ea80c72bffde2e9e053e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cc82c6dff548f0066a51a6e577c7454e7d26a968

Published CVSS scores

5.5National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5SUSECVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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