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X.Org X Server EUVD-2026-27343

| CVE-2026-34002 MEDIUM
Buffer Access with Incorrect Length Value (CWE-805)
2026-05-05 redhat
Denial Of Service Buffer Overflow Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9
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.

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Connect to local X11 socket
Exploit
Craft malformed XKB modifier map request
Execution
Trigger out-of-bounds read in XKB parser
Impact
Read sensitive memory or crash server
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Vulnerability AssessmentAI

Exploitation Exploitation requires the attacker to have local system access with valid user credentials to connect to the X11 server socket. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment CVSS 6.1 with attack vector local and privilege level low indicates moderate real-world risk. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario A local unprivileged user on a multi-user RHEL system connects to the X11 server and sends a specially crafted XKB modifier map request via the X protocol. The malformed request causes the server's XKB parser to calculate an invalid memory offset when reading modifier definitions, leading to an out-of-bounds read. …
Remediation 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. … Detailed patch versions, workarounds, and compensating controls in full report.
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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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