Bug 2451112 (CVE-2026-34002)

Summary: CVE-2026-34002 xorg: xwayland: X.Org X server: Information disclosure or Denial of Service via out-of-bounds read in XKB modifier map handling
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, security-response-team, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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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.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-03-25 07:10:36 UTC 
Out-of-bounds Read vulnerability in the XKB modifier map request handling of the X.Org X server. The function CheckModifierMap() processes wire data in a loop but does not sufficiently verify that the remaining bytes are within the bounds of the client request. As a result, the total number of keys processed can exceed the actual data supplied by the client, causing reads of uninitialized memory beyond the request buffer. An attacker with access to the X11 server can trigger this without user interaction, potentially disclosing memory and/or crashing the service.