Stack-based buffer overflow in X.Org X server/Xwayland _XkbSetMapChecks
CVE-2026-50259 is a stack-based buffer overflow in the X.Org X server and Xwayland XKB SetMap request handling. In _XkbSetMapChecks(), the code declares a fixed-size stack buffer, mapWidths[256], indexed by key type index. The helper function CheckKeyTypes() can write to this buffer using a client-controlled offset, allowing writes past the end of the stack buffer. The issue affects X.Org X server versions prior to 21.1.23 and Xwayland versions prior to 24.1.12.
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Impact, mitigation & remediation
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Impact
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Mitigation
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Remediation
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Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
6 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.
No news coverage yet. Advisories and community discussion only.
The version that knows your environment.
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Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.