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Fencer Vulns
high 7.5

CVE-2026-11771 json

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 authent…

published 2026-07-30 3 mo ago modified 2026-08-05 3 mo ago also EUVD-2026-51237

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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

Patch / fix

  • openvpn openvpn 2.6.21, 2.7.5
  • openvpn Debian 12 2.6.14-0+deb12u2
  • openvpn Debian 13 2.6.14-1+deb13u3
  • openvpn Debian 14 2.7.5-1

debian advisories DEBIAN-CVE-2026-11771

  • openvpn Ubuntu 24.04 LTS 2.6.19-0ubuntu0.24.04.3
  • openvpn Ubuntu 26.04 LTS 2.7.0-1ubuntu1.2

ubuntu advisories UBUNTU-CVE-2026-11771

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openvpn SLES for SAP applications 16.0, SLES 16.0 2.6.10-160000.5.1
  • openvpn SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 2.6.10-150600.3.26.1
  • openvpn-dco SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 2.6.10-150600.3.26.1

suse advisories SUSE-SU-2026:24220-1SUSE-SU-2026:3596-1

  • openvpn openSUSE Leap 16.0 2.6.10-160000.5.1

opensuse advisories openSUSE-SU-2026:22072-1

  • openvpn Alpine 3.24 2.7.5-r0

alpine advisories ALPINE-CVE-2026-11771

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-11771 updated cvss 5.3

openvpn: OpenVPN: Denial of Service via crafted NTLM proxy response

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 7.0 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
CNA 4.0 7.0 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • OpenVPN OpenVPN

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.