CVE-2023-1393

Local privilege escalation via stale overlay pointer

Published Mar 30, 2023 · Updated Jan 22, 2026

Use-after-free in X.Org Server before 21.1.8 allows local users to escalate privileges by destroying the compositor overlay window. The destruction path frees that window but leaves its pointer in CompScreen, and later code dereferences the stale pointer. An attacker must be an authorized local X client; the resulting memory corruption can crash the server or elevate the client's privileges.

CVSS severity7.8
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in X.Org Server before 21.1.8 allows local users to escalate privileges by destroying the compositor overlay window. The destruction path frees that window but leaves its pointer in CompScreen, and later code dereferences the stale pointer. An attacker must be an authorized local X client; the resulting memory corruption can crash the server or elevate the client's privileges.

The record

CVE
CVE-2023-1393
Published
Mar 30, 2023
Updated
Jan 22, 2026
Vendor
X.Org
Product
X.Org Server
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 30, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 22, 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=xorg-server 21.1.8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

X.Org · X.Org Serverversion=xorg-server 21.1.8

Published CVSS scores

7.8NIST NVDCVSS: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

CWE-416Use After Free
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

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Your stack

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