CVE-2023-1393

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-03-30 · updated 2026-06-17
Weakness: CWE-416

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.

Affected products

Fedoraproject Fedora: 36, 37, 38
xorg-x11-server: before 21.1.8 — fixed in 21.1.8

How to fix

Upgrade to a fixed version: xorg-x11-server 21.1.8. Check the vendor advisory for mitigations.

References

https://gitlab.freedesktop.org/xorg/xserver/-/commit/26ef545b3502f61ca722a7a3373507e88ef64110
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/H3EVO3OQV6T4BSABWZ2TU3PY5TJTEQZ2/
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/NOYATGGPMT3COC7ELAJW5TG2PVS3AFR2/
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/QHJMSMK7G4GPLMKIGKXIOL2RTKU5VFWE/
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/SWFUDSBSABRHQOX6TIQ5O3SNPFTPFQQP/
https://security.gentoo.org/glsa/202305-30
https://www.openwall.com/lists/oss-security/2023/03/29/1
https://gitlab.freedesktop.org/xorg/xserver/-/commit/26ef545b3502f61ca722a7a3373507e88ef64110

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