CVE-2026-31693

Local privilege escalation via stale CIFS replay state

Published Apr 30, 2026 · Updated Apr 30, 2026

Memory corruption in the Linux kernel CIFS client allows local users to escalate privileges through replayed filesystem requests. The smb2_set_ea, smb2_ioctl_query_info, and smb311_posix_mkdir replay paths fail to reset used_len, buffer, and pc_buf, allowing stale lengths or freed pointers to be reused. Reachability requires an existing CIFS mount and a retryable reconnect error; an unprivileged caller can invoke ioctl, setxattr, or mkdir operations, causing kernel disclosure, corruption, or a crash.

CVSS severity7.8
High
EPSS probability0.13%
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 corruption in the Linux kernel CIFS client allows local users to escalate privileges through replayed filesystem requests. The smb2_set_ea, smb2_ioctl_query_info, and smb311_posix_mkdir replay paths fail to reset used_len, buffer, and pc_buf, allowing stale lengths or freed pointers to be reused. Reachability requires an existing CIFS mount and a retryable reconnect error; an unprivileged caller can invoke ioctl, setxattr, or mkdir operations, causing kernel disclosure, corruption, or a crash.

The record

CVE
CVE-2026-31693
Published
Apr 30, 2026
Updated
Apr 30, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 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 <14f66f44646333d2bfd7ece36585874fd72f8286
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1d731e512134495e0ef490ade0e4d91dc0d515ec
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7c9ce68192eef14c777cb6ce17155d2eb2431aea
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c854ab481ece4b3e5f4c2e8b22824f015ff874a5
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c99e160938b627f6f28edee930e8abc157e84386

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <14f66f44646333d2bfd7ece36585874fd72f8286; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1d731e512134495e0ef490ade0e4d91dc0d515ec; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7c9ce68192eef14c777cb6ce17155d2eb2431aea; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c854ab481ece4b3e5f4c2e8b22824f015ff874a5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c99e160938b627f6f28edee930e8abc157e84386

Published CVSS scores

7.8Linux kernel.org CNACVSS:3.1/AV:L/AC:L/PR:L/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.

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

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