Xwayland: xorg: x.org x server: information disclosure and denial of service via out-of-bounds read in xkb geometry processing.
Summary
| CVE | CVE-2026-34000 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-05 16:16:11 UTC |
| Updated | 2026-05-07 14:35:33 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 9.1 CRITICAL from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS: 0.000290000 probability, percentile 0.082800000 (date 2026-05-11)
Problem Types: CWE-125 | CWE-125 Out-of-bounds Read
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
| 3.1 | [email protected] | Secondary | 6.1 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L |
| 3.1 | CNA | CVSS | 6.1 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Operating System | Redhat | Enterprise Linux | 10.0 | All | All | All |
| Operating System | Redhat | Enterprise Linux | 6.0 | All | All | All |
| Operating System | Redhat | Enterprise Linux | 7.0 | All | All | All |
| Operating System | Redhat | Enterprise Linux | 8.0 | All | All | All |
| Operating System | Redhat | Enterprise Linux | 9.0 | All | All | All |
| Application | X.org | X Server | - | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | Issue Tracking, Third Party Advisory |
| access.redhat.com/security/cve/CVE-2026-34000 | [email protected] | access.redhat.com | Third Party Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank Jan-Niklas Sohn (TrendAI Zero Day Initiative) for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-03-25T06:37:44.196Z | Reported to Red Hat. |
| CNA | 2026-05-05T14:01:15.690Z | Made public. |
Workarounds
CNA: To mitigate this vulnerability, restrict access to the X11 server. On systems where a graphical environment is not required, consider disabling the X server entirely by setting the default system target to multi-user mode. For systems requiring the X server, ensure that X11 forwarding is disabled in SSH configurations if not explicitly needed, and restrict direct X11 connections to trusted users and networks through firewall rules. If changes are made to SSH configuration, the `sshd` service must be restarted. If the default system target is changed, a system reboot is required.