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CVE-2026-81738 is an off-by-one out-of-bounds write in OpenVPN for Windows versions 2.5.0 through 2.7.6 when using the tap-windows6 driver. The flaw is in write_dhcp_search_str(), which constructs DHCP DOMAIN-SEARCH options for the Windows TUN/TAP DHCP masquerade path. Specially crafted search-domain entries whose accumulated length reaches the temporary-buffer boundary can cause a one-byte stack-buffer overflow.
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A Windows OpenVPN single-byte buffer-overflow vulnerability in write_dhcp_search_str(), caused by an off-by-one temporary-buffer guard error and triggerable through crafted DHCP search-domain options.
A Windows OpenVPN off-by-one error in write_dhcp_search_str() that permits a one-byte temporary-buffer overflow through specially crafted DHCP search-domain options.
An out-of-bounds write vulnerability in OpenVPN versions 2.5.0 through 2.7.6 on Windows when using the tap-windows6 driver. Crafted DOMAIN-SEARCH entries can trigger the flaw.
A medium-severity, Windows-only OpenVPN off-by-one stack-buffer overflow in the DHCP masquerade path. A malicious or controlling OpenVPN server can push crafted DHCP DOMAIN-SEARCH options that trigger a one-byte stack overflow.
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Cross-references every affected SKU, including bundled OEM variants.
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