Bug 2509516 (CVE-2026-11771)

Summary: CVE-2026-11771 openvpn: OpenVPN: Denial of Service via crafted NTLM proxy response
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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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.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2509669, 2509668    
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Description OSIDB Bzimport 2026-07-30 17:01:46 UTC
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