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X.Org X Server EUVDEUVD-2026-27343

| CVE-2026-34002 MEDIUM
Buffer Access with Incorrect Length Value (CWE-805)
2026-05-05 redhat
6.1
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
6.1 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
SUSE
MEDIUM
qualitative
Red Hat
6.1 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
Low

Lifecycle Timeline

1
Analysis Generated
May 05, 2026 - 16:31 vuln.today

DescriptionCVE.org

A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.

AnalysisAI

Out-of-bounds read in X.Org X Server XKB modifier map handling allows local authenticated attackers to read sensitive memory or crash the server by sending malformed X11 requests. The vulnerability affects RHEL 6 through 10 and requires local access with user-level privileges; exploitation results in information disclosure or denial of service.

Technical ContextAI

The X.Org X Server implements the X Keyboard Extension (XKB) protocol for handling keyboard input and modifiers. The vulnerability resides in the XKB modifier map parsing logic, which fails to validate buffer boundaries when processing modifier key definitions. This is a classic CWE-805 buffer over-read vulnerability where memory access calculations do not account for valid buffer limits. Attackers with local X11 server access can craft malformed XKB requests that trigger reads beyond allocated memory regions, exposing adjacent heap or stack data or triggering server crashes through invalid memory access.

RemediationAI

Apply the security update released by Red Hat for your RHEL version: RHEL 6 users should update the xorg-x11-server package, RHEL 7 users should update xorg-x11-server, RHEL 8 users should update xorg-x11-server, RHEL 9 users should update xorg-x11-server, and RHEL 10 users should update xorg-x11-server to patched versions available via Red Hat errata. Check the Red Hat security advisory at https://access.redhat.com/security/cve/CVE-2026-34002 for exact patched package versions and installation commands. As a temporary compensating control, restrict X11 server access to trusted local users only by reviewing display permissions and removing unnecessary X11 forwarding capabilities. Disable XKB extensions if not required in your deployment using xkb-config directives in xorg.conf, though this may limit keyboard functionality for international users.

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
Image SLES-SAPCAL-Azure Image SLES-SAPCAL-EC2 Image SLES-SAPCAL-GCE Affected
Image SLES15-SP4-SAP Image SLES15-SP4-SAP-Azure Image SLES15-SP4-SAP-EC2 Image SLES15-SP4-SAP-GCE Image SLES15-SP4-SAPCAL Image SLES15-SP4-SAPCAL-Azure Image SLES15-SP4-SAPCAL-EC2 Image SLES15-SP4-SAPCAL-GCE Affected
Image SLES15-SP5-SAPCAL-Azure Image SLES15-SP5-SAPCAL-EC2 Image SLES15-SP5-SAPCAL-GCE Affected
Image SLES15-SP6-SAP Image SLES15-SP6-SAP-Azure Image SLES15-SP6-SAP-EC2 Image SLES15-SP6-SAP-GCE Image SLES15-SP6-SAPCAL Image SLES15-SP6-SAPCAL-Azure Image SLES15-SP6-SAPCAL-EC2 Image SLES15-SP6-SAPCAL-GCE Affected
Image SLES15-SP7-SAPCAL-Azure Image SLES15-SP7-SAPCAL-EC2 Image SLES15-SP7-SAPCAL-GCE Affected

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EUVD-2026-27343 vulnerability details – vuln.today

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