CVE-2026-31711Network attack vector

Pre-authentication service interruption via connection-slot leak

Published May 1, 2026 · Updated May 1, 2026

Resource exhaustion in Linux Kernel ksmbd allows remote attackers to interrupt SMB service through unauthenticated TCP connections. The ksmbd_tcp_new_connection function returns after alloc_transport fails without decrementing active_num_conn, permanently consuming a max_connections slot. Reaching the fault requires pre-authentication memory pressure; exhausting the counter rejects every later SMB connection until module reload or reboot.

CVSS severity7.5
High
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Linux Kernel ksmbd allows remote attackers to interrupt SMB service through unauthenticated TCP connections. The ksmbd_tcp_new_connection function returns after alloc_transport fails without decrementing active_num_conn, permanently consuming a max_connections slot. Reaching the fault requires pre-authentication memory pressure; exhausting the counter rejects every later SMB connection until module reload or reboot.

The record

CVE
CVE-2026-31711
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-401, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <283027aa93380380a0994f35dde3ec95318f2654
  2. Affected versionversion=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <295a9fc6789d1011c36ded9f0f2907bb34fa0de4
  3. Affected versionversion=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <6551300dc452ac16a855a83dbd1e74899542d3b3
  4. Affected versionversion=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <97f8d2648ef4871e4cd335e2d769cb40054a6772
  5. Affected versionversion=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <fb48185bcd946d42de7017cf27f912f8ab26acf0
  6. Affected versionversion=4210c3555db4b38bade92331b153e583261f05f9
  7. Affected versionversion=6.2
  8. Affected versionversion=d5d7847e57ac69fa99c18b363a34419bcdb5a281

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <283027aa93380380a0994f35dde3ec95318f2654; version=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <295a9fc6789d1011c36ded9f0f2907bb34fa0de4; version=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <6551300dc452ac16a855a83dbd1e74899542d3b3; version=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <97f8d2648ef4871e4cd335e2d769cb40054a6772; version=0d0d4680db22eda1eea785c47bbf66a9b33a8b16 <fb48185bcd946d42de7017cf27f912f8ab26acf0; version=4210c3555db4b38bade92331b153e583261f05f9; version=6.2; version=d5d7847e57ac69fa99c18b363a34419bcdb5a281

Published CVSS scores

7.5kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
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.

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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