{
  "threat_severity" : "Moderate",
  "public_date" : "2026-07-30T16:36:41Z",
  "bugzilla" : {
    "description" : "openvpn: OpenVPN: Denial of Service via crafted NTLM proxy response",
    "id" : "2509516",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2509516"
  },
  "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" : [ "OpenVPN version 2.1.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 allows attackers via an off-by-one buffer write in the NTLM proxy authentication to potentially cause a crash via a crafted NTLM response from a malicious proxy server", "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." ],
  "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.",
  "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" ],
  "name" : "CVE-2026-11771",
  "csaw" : false
}