CVE-2026-11771

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{"bugzilla": {"description": "openvpn: OpenVPN: Denial of Service via crafted NTLM proxy response", "id": "2509516", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2509516"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-787", "details": ["A flaw was found in OpenVPN. A remote attacker could exploit an off-by-one buffer write vulnerability during NTLM (NT LAN Manager) proxy authentication. By sending a specially crafted NTLM response from a malicious proxy server, the attacker could cause the OpenVPN client to crash, leading to a denial of service."], "name": "CVE-2026-11771", "public_date": "2026-07-30T16:36:41Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-11771\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-11771\nhttps://community.openvpn.net/ReleaseHistory#openvpn-2621-released-1-july-2026\nhttps://community.openvpn.net/ReleaseHistory#openvpn-275-released-1-july-2026\nhttps://community.openvpn.net/Security%20Announcements/CVE-2026-11771"], "statement": "This Moderate impact flaw in OpenVPN clients allows a denial of service via an off-by-one buffer write during NTLM proxy authentication. Exploitation requires a client to connect through a malicious NTLM proxy server, which can then send a specially crafted response. The necessity of user interaction with a compromised proxy limits the overall risk.", "threat_severity": "Moderate"}

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