CVE-2026-31610Network attack vector

Pre-authentication memory exhaustion via skipped mechToken free

Published Apr 24, 2026 · Updated Apr 24, 2026

Memory leak in ksmbd SPNEGO handling in Linux Kernel allows remote attackers to exhaust server memory before authentication. ksmbd_neg_token_alloc() stores a copied mechToken, but smb2_sess_setup() skips kfree() when a later malformed element makes decoding clear use_spnego. Repeated malformed session-setup blobs slowly consume kernel memory without credentials and can interrupt availability when memory is exhausted.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Memory leak in ksmbd SPNEGO handling in Linux Kernel allows remote attackers to exhaust server memory before authentication. ksmbd_neg_token_alloc() stores a copied mechToken, but smb2_sess_setup() skips kfree() when a later malformed element makes decoding clear use_spnego. Repeated malformed session-setup blobs slowly consume kernel memory without credentials and can interrupt availability when memory is exhausted.

The record

CVE
CVE-2026-31610
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-401, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <269c800a7a7e363459291885b35f7bc72e231ed6
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6c8c44e6553b9f072f62d9875e567766eb293162
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dd53414e301beb915fe672dc4c4a51bafb917604
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dd577cb55588ec3fbc66af3621280306601c4192

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <269c800a7a7e363459291885b35f7bc72e231ed6; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6c8c44e6553b9f072f62d9875e567766eb293162; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dd53414e301beb915fe672dc4c4a51bafb917604; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dd577cb55588ec3fbc66af3621280306601c4192

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.

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

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
T1499.004Application or System Exploitation

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo