CVE-2023-2640Public exploit

Local root escalation via unchecked OverlayFS xattrs

Published Jul 26, 2023 · Updated Oct 23, 2024

Incorrect authorization in Canonical Ubuntu Kernel allows local users to gain root privileges through crafted OverlayFS mounts. The Ubuntu-specific OverlayFS copy-up path transfers attacker-set trusted.overlayfs.* extended attributes to upper files without the required permission checks. Exploitation requires low-privileged local access and unprivileged user namespaces, and it can turn file capabilities into root-level code execution.

CVSS severity7.8
High
EPSS probability15.20%
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

Incorrect authorization in Canonical Ubuntu Kernel allows local users to gain root privileges through crafted OverlayFS mounts. The Ubuntu-specific OverlayFS copy-up path transfers attacker-set trusted.overlayfs.* extended attributes to upper files without the required permission checks. Exploitation requires low-privileged local access and unprivileged user namespaces, and it can turn file capabilities into root-level code execution.

The record

CVE
CVE-2023-2640
Published
Jul 26, 2023
Updated
Oct 23, 2024
Vendor
Canonical
Product
Ubuntu Kernel
Classifications
CWE-863, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 26, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 23, 2024Record 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=0 <5.4.0-155.172
  2. Affected versionversion=0 <6.0.0-1020.20
  3. Affected versionversion=0 <6.2.0-26.26

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Canonical · Ubuntu Kernelversion=0 <5.4.0-155.172; version=0 <6.0.0-1020.20; version=0 <6.2.0-26.26

Published CVSS scores

7.8Canonical Ltd.CVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1068Exploitation for Privilege Escalation

Public exploit references

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