CVE-2026-31707

Kernel memory disclosure or crash via response-size overflow

Published May 1, 2026 · Updated May 1, 2026

Integer overflow in ksmbd in Linux Kernel releases with the affected code allows local users to disclose kernel memory or crash the system. ipc_validate_msg() adds payload_sz or multiplies ngroups in unsigned size calculations without overflow checks, allowing wrapped lengths to pass validation before memcpy or kmemdup trusts them. Exploitation requires low-privileged local access and control of a ksmbd.mountd response; the bounded outcomes are kernel-memory disclosure and a system crash.

CVSS severity7.1
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in ksmbd in Linux Kernel releases with the affected code allows local users to disclose kernel memory or crash the system. ipc_validate_msg() adds payload_sz or multiplies ngroups in unsigned size calculations without overflow checks, allowing wrapped lengths to pass validation before memcpy or kmemdup trusts them. Exploitation requires low-privileged local access and control of a ksmbd.mountd response; the bounded outcomes are kernel-memory disclosure and a system crash.

The record

CVE
CVE-2026-31707
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-787
Attack vector
local
Privileges
authenticated

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

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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=0626e6641f6b467447c81dd7678a69c66f7746cf <299db777ea0cfa5c407e41b045c24a14c034c27b
  2. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <7dd0c858e1909769a4c91842724315ee74f1a5f1
  3. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <99c631d0366c1eab8fb188fe66425f4581ebdde4
  4. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <d6a6aa81eac2c9bff66dc6e191179cb69a14426b
  5. Affected versionversion=5.15

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0626e6641f6b467447c81dd7678a69c66f7746cf <299db777ea0cfa5c407e41b045c24a14c034c27b; version=0626e6641f6b467447c81dd7678a69c66f7746cf <7dd0c858e1909769a4c91842724315ee74f1a5f1; version=0626e6641f6b467447c81dd7678a69c66f7746cf <99c631d0366c1eab8fb188fe66425f4581ebdde4; version=0626e6641f6b467447c81dd7678a69c66f7746cf <d6a6aa81eac2c9bff66dc6e191179cb69a14426b; version=5.15

Published CVSS scores

7.1kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write

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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