Upwind Security MDR@UpwindMDR
Disclosure
🚨High - OpenVPN NTLM Proxy Auth Off-by-One OOB Write DoS (CVE-2026-11771) OpenVPN’s NTLM proxy authentication handling contains an off-by-one out-of-bounds write when parsing a crafted NTLM response from a malicious HTTP proxy. A proxy-in-the-middle can trigger a client crash, causing denial of service. Setups not using NTLM proxy auth aren’t impacted. 👉Affected: OpenVPN 2.1.0-2.6.20, 2.7_alpha1-2.7.4
Post summary
OpenVPN’s NTLM proxy authentication handling has an off‑by‑one OOB write that can crash clients and cause DoS on affected versions.
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