CVE-2026-31705Network attack vector

Kernel heap overwrite via unchecked EA padding

Published May 1, 2026 · Updated May 1, 2026

An out-of-bounds write in Linux Kernel ksmbd allows remote attackers to overwrite adjacent kernel heap memory via compound SMB requests. The smb2_get_ea() handler subtracts the EA value length but then applies 4-byte alignment with an unchecked memset(), writing 1–3 NUL bytes past a full response buffer. Exploitation requires an enabled, network-reachable ksmbd service and a compound request that leaves the QUERY_INFO EA response with no room for padding.

CVSS severity9.8
Critical
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An out-of-bounds write in Linux Kernel ksmbd allows remote attackers to overwrite adjacent kernel heap memory via compound SMB requests. The smb2_get_ea() handler subtracts the EA value length but then applies 4-byte alignment with an unchecked memset(), writing 1–3 NUL bytes past a full response buffer. Exploitation requires an enabled, network-reachable ksmbd service and a compound request that leaves the QUERY_INFO EA response with no room for padding.

The record

CVE
CVE-2026-31705
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-787, T1190
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=6.6
  2. Affected versionversion=9f297df20d93411c0b4ddad7f88ba04a7cd36e77
  3. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <30010c952077a1c89ecdd71fc4d574c75a8f5617
  4. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <790304c02bf9bd7b8171feda4294d6e62d32ae8f
  5. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <922d48fe8c19f388ffa2f709f33acaae4e408de2
  6. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <98f3de6ef4efbd899348d333f0902dc4ff14380c
  7. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <ffbce350c6fd1e99116ea57383b9031717e36d3b
  8. Affected versionversion=f2283680a80571ca82d710bc6ecd8f8beac67d63

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.6; version=9f297df20d93411c0b4ddad7f88ba04a7cd36e77; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <30010c952077a1c89ecdd71fc4d574c75a8f5617; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <790304c02bf9bd7b8171feda4294d6e62d32ae8f; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <922d48fe8c19f388ffa2f709f33acaae4e408de2; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <98f3de6ef4efbd899348d333f0902dc4ff14380c; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <ffbce350c6fd1e99116ea57383b9031717e36d3b; version=f2283680a80571ca82d710bc6ecd8f8beac67d63

Published CVSS scores

9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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-787Out-of-bounds Write
T1190Exploit Public-Facing Application

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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