CVE-2026-31433Network attack vector

Memory corruption via unchecked filename conversion

Published Apr 22, 2026 · Updated Apr 22, 2026

Out-of-bounds write in Linux Kernel ksmbd allows remote authenticated users to corrupt kernel memory via compound SMB requests. get_file_all_info() fails to validate the client-provided OutputBufferLength and passes PATH_MAX to smbConvertToUTF16(), so filename conversion writes beyond the remaining response buffer. Network access to an active ksmbd server and low SMB privileges are required; the published record establishes memory corruption, not code execution.

CVSS severity8.8
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Linux Kernel ksmbd allows remote authenticated users to corrupt kernel memory via compound SMB requests. get_file_all_info() fails to validate the client-provided OutputBufferLength and passes PATH_MAX to smbConvertToUTF16(), so filename conversion writes beyond the remaining response buffer. Network access to an active ksmbd server and low SMB privileges are required; the published record establishes memory corruption, not code execution.

The record

CVE
CVE-2026-31433
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 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 <4cca3eff2099b18672934a39cee70aed835d652c
  3. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <358cdaa1f7fbf2712cb4c5f6b59cb9a5c673c5fe
  4. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <7aec5a769d2356cbf344d85bcfd36de592ac96a5
  5. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <9d7032851d6f5adbe2739601ca456c0ad3b422f0
  6. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <b0cd9725fe2bcc9f37d096b132318a9060373f5d
  7. Affected versionversion=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <beef2634f81f1c086208191f7228bce1d366493d
  8. Affected versionversion=f2283680a80571ca82d710bc6ecd8f8beac67d63 <3a852f9d1c981fb14f6bf4e24999e0ea8088a7d7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.6; version=9f297df20d93411c0b4ddad7f88ba04a7cd36e77 <4cca3eff2099b18672934a39cee70aed835d652c; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <358cdaa1f7fbf2712cb4c5f6b59cb9a5c673c5fe; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <7aec5a769d2356cbf344d85bcfd36de592ac96a5; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <9d7032851d6f5adbe2739601ca456c0ad3b422f0; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <b0cd9725fe2bcc9f37d096b132318a9060373f5d; version=e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d <beef2634f81f1c086208191f7228bce1d366493d; version=f2283680a80571ca82d710bc6ecd8f8beac67d63 <3a852f9d1c981fb14f6bf4e24999e0ea8088a7d7

Published CVSS scores

8.8Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.8Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
8.7UbuntuCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
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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