{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-11771", "assignerOrgId": "36a55730-e66d-4d39-8ca6-3c3b3017965e", "state": "PUBLISHED", "assignerShortName": "OpenVPN", "dateReserved": "2026-06-09T11:44:10.570Z", "datePublished": "2026-07-30T16:36:41.087Z", "dateUpdated": "2026-07-30T18:04:42.335Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "36a55730-e66d-4d39-8ca6-3c3b3017965e", "shortName": "OpenVPN", "dateUpdated": "2026-07-30T16:36:41.087Z"}, "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-193", "description": "CWE-193 Off-by-one error", "type": "CWE"}]}, {"descriptions": [{"lang": "en", "cweId": "CWE-121", "description": "CWE-121 Stack-based buffer overflow", "type": "CWE"}]}, {"descriptions": [{"lang": "en", "cweId": "CWE-787", "description": "CWE-787 Out-of-bounds write", "type": "CWE"}]}], "affected": [{"vendor": "OpenVPN", "product": "OpenVPN", "versions": [{"status": "affected", "version": "2.1.0", "lessThanOrEqual": "2.6.20", "versionType": "semver"}, {"status": "affected", "version": "2.7_alpha1", "lessThanOrEqual": "2.7.4", "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "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"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "HIGH", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 7, "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H"}}], "references": [{"tags": ["vendor-advisory"], "url": "https://community.openvpn.net/Security%20Announcements/CVE-2026-11771"}, {"url": "https://community.openvpn.net/ReleaseHistory#openvpn-275-released-1-july-2026", "tags": ["release-notes"]}, {"url": "https://community.openvpn.net/ReleaseHistory#openvpn-2621-released-1-july-2026", "tags": ["release-notes"]}], "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-07-30T18:04:28.530958Z", "id": "CVE-2026-11771", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-30T18:04:42.335Z"}}]}}

{}

{}

{"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"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2.1.0,2.6.20]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[2.7_alpha1,2.7.4]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "OpenVPN", "source": "cna", "vendor": "OpenVPN"}, "product": "openvpn", "vendor": "openvpn"}], "created": "2026-07-30T18:30:04.720629+00:00", "updated": "2026-07-30T18:30:04.720648+00:00", "vendors": ["openvpn", "openvpn$PRODUCT$openvpn"]}