CVE-2025-26599: Xorg: xwayland: use of uninitialized pointer in compredirectwindow()

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: 2025-02-25 · updated 2026-06-29
Weakness: CWE-824

Description

An access to an uninitialized pointer flaw was found in X.Org and Xwayland. The function compCheckRedirect() may fail if it cannot allocate the backing pixmap. In that case, compRedirectWindow() will return a BadAlloc error without validating the window tree marked just before, which leaves the validated data partly initialized and the use of an uninitialized pointer later.

Affected products

Red Hat Enterprise Linux: 7.0, 8.0, 9.0
Kaspersky TigerVNC: all versions
xorg-x11-server: before 21.1.16 — fixed in 21.1.16
X.Org xwayland: before 24.1.6 — fixed in 24.1.6

How to fix

Upgrade to a fixed version: xorg-x11-server 21.1.16; X.Org xwayland 24.1.6. Check the vendor advisory for mitigations.

References

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