Debian Linux - openvpn - None

Ubuntu Linux - 1-byte buffer overrun on NTLMv2 proxy responses

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1990 advisory.

    An attacker controlling an HTTP proxy (or performing MITM on the plaintext pre-TLS proxy connection) can     trigger a single 0-byte overrun to a buffer on the stack by sending a crafted NTLM Type 2 challenge     response. (CVE-2026-11771)

    If the active TLS session has a pending dedicated ACK packet, tls_multi_process sets to_link to     ks->ack_write_buf. If in the same execution of tls_multi_process, the initializing session reaches the     authenticated stage, the active session will be freed which leaves to_link.data pointing to freed memory.
    (CVE-2026-12996)

    openvpn Server crash on reception of suitably malformed auth-token, if --auth-gen-token external-auth is     active (CVE-2026-13122)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-8540-1 advisory.

    It was discovered that OpenVPN had a 1-byte buffer overrun when handling NTLMv2 proxy responses. An     attacker could use this issue to cause a denial of service or possibly execute arbitrary code. This issue     only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-11771)

    It was discovered that OpenVPN incorrectly handled metadata when extracting tls-crypt-v2 client keys. An     attacker could possibly use this issue to obtain sensitive information. (CVE-2026-12932)

    It was discovered that OpenVPN had a use-after-free in the ack_write_buf handling. An attacker could use     this issue to cause OpenVPN to crash, resulting in a denial of service, or possibly execute arbitrary     code. (CVE-2026-12996)

    It was discovered that OpenVPN had a use-after-free in the tls_wrap_reneg handling. An attacker could use     this issue to cause OpenVPN to crash, resulting in a denial of service, or possibly execute arbitrary     code. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-13117)

    It was discovered that OpenVPN incorrectly validated authentication tokens when external authentication     was enabled. A remote attacker could possibly use this issue to cause OpenVPN to crash, resulting in a     denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-13122)

    It was discovered that OpenVPN had a memory leak when handling tls-crypt-v2 client keys. A remote attacker     with a valid tls-crypt-v2 client key could possibly use this issue to cause OpenVPN to consume excessive     resources, leading to a denial of service. (CVE-2026-13698)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - A memory leak in OpenVPN version 2.5.0 through 2.5.11, 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4
    allows remote attackers with a valid tls-crypt-v2 client key to potentially cause a denial of service
    (CVE-2026-13698)

According to its self-reported version number, the version of OpenVPN installed on the remote Windows host is affected by multiple vulnerabilities:

  - A use-after-free bug in ack_write_buf(), triggerable by a well-timed sequence of control channel and     authentication packets. (CVE-2026-12996)

  - A use-after-free bug in tls_wrap_reneg(), triggerable by a suitable sequence of dynamic tls-crypt     control-channel packets. (CVE-2026-13117)

  - A possible 1-byte buffer overrun on NTLMv2 proxy responses. (CVE-2026-11771)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 12 host has a package installed that is affected by multiple vulnerabilities as referenced in the dla-4666 advisory.

    - -----------------------------------------------------------------------     Debian LTS Advisory DLA-4666-1              debian-lts@lists.debian.org     https://www.debian.org/lts/security/                      Utkarsh Gupta     July 04, 2026                               https://wiki.debian.org/LTS
    - -----------------------------------------------------------------------

    Package        : openvpn     Version        : 2.6.14-0+deb12u2     CVE ID         : CVE-2026-11771 CVE-2026-12932 CVE-2026-12996 CVE-2026-13117                      CVE-2026-13122 CVE-2026-13698

    Multiple security vulnerabilities were discovered in OpenVPN, which     could result in denial of service.

    For Debian 12 bookworm, these problems have been fixed in version     2.6.14-0+deb12u2.

    We recommend that you upgrade your openvpn packages.

    For the detailed security status of openvpn please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/openvpn

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 13 host has a package installed that is affected by multiple vulnerabilities as referenced in the dsa-6376 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6376-1                   security@debian.org     https://www.debian.org/security/                       Moritz Muehlenhoff     July 03, 2026                         https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : openvpn     CVE ID         : CVE-2026-11771 CVE-2026-12932 CVE-2026-12996                      CVE-2026-13117 CVE-2026-13122 CVE-2026-13698

    Multiple security vulnerabilities were discovered in OpenVPN, which     could result in denial of service.

    For the stable distribution (trixie), these problems have been fixed in     version 2.6.14-1+deb13u3.

    We recommend that you upgrade your openvpn packages.

    For the detailed security status of openvpn please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/openvpn

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the ffa897a0-756f-11f1-b291-a74de6bb0320 advisory.

    The OpenVPN community project team reports:
    [...] OpenVPN 2.7.5 [...] is a bugfix release fixing several security issues:

Tenable has extracted the preceding description block directly from the FreeBSD security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - The vulnerability exists due to a 1-byte buffer overrun condition within the NTLMv2 proxy authentication     parsing pipeline. When configured to route traffic through an HTTP proxy, an unauthenticated proxy or     network attacker can intercept and return a malformed NTLMv2 response header, triggering memory corruption     that crashes the client or server daemon. (CVE-2026-11771)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
328485	Amazon Linux 2023 : openvpn, openvpn-devel (ALAS2023-2026-1990)	Nessus	Amazon Linux Local Security Checks	medium
326999	Ubuntu 22.04 LTS / 24.04 LTS / 26.04 LTS : OpenVPN vulnerabilities (USN-8540-1)	Nessus	Ubuntu Local Security Checks	medium
444654	Alpine: multiple openvpn packages: security update to 2.7.5-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	medium
444654	Alpine: multiple openvpn packages: security update to 2.7.5-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	medium
325894	OpenVPN 2.6.0 < 2.6.21 / 2.7.x < 2.7.5 Multiple Vulnerabilities	Nessus	Windows	medium
325054	Debian dla-4666 : openvpn - security update	Nessus	Debian Local Security Checks	medium
325052	Debian dsa-6376 : openvpn - security update	Nessus	Debian Local Security Checks	medium
324994	FreeBSD : openvpn -- multiple vulnerabilities (ffa897a0-756f-11f1-b291-a74de6bb0320)	Nessus	FreeBSD Local Security Checks	medium
324930	Linux Distros Unpatched Vulnerability : CVE-2026-11771	Nessus	Misc.	critical

Detections

Analytics

CVE-2026-11771

critical

Tenable Plugins

medium

medium

medium

medium

medium

medium

medium

medium

critical