X509 certificate verification was not correctly implemented in the IP Intelligence Subscription and IP Intelligence feed-list features, and thus the remote server's identity is not properly validated in F5 BIG-IP 12.0.0-12.1.2, 11.6.0-11.6.2, or 11.5.0-11.5.5.

In F5 BIG-IP PEM 12.1.0 through 12.1.2 when downloading the Type Allocation Code (TAC) database file via HTTPS, the server's certificate is not verified. Attackers in a privileged network position may be able to launch a man-in-the-middle attack against these connections. TAC databases are used in BIG-IP PEM for Device Type and OS (DTOS) and Tethering detection. Customers not using BIG-IP PEM, not configuring downloads of TAC database files, or not using HTTP for that download are not affected.

Affected versions of CODESYS Git in Versions prior to V1.1.0.0 lack certificate validation in HTTPS handshakes. CODESYS Git does not implement certificate validation by default, so it does not verify that the server provides a valid and trusted HTTPS certificate. Since the certificate of the server to which the connection is made is not properly verified, the server connection is vulnerable to a man-in-the-middle attack.

Missing SSL Certificate Validation issue exists in Pluck 4.7.15 in update_applet.php, which could lead to man-in-the-middle attacks.

Google Chrome before 18.0.1025.142 does not properly check X.509 certificates before use of a SPDY proxy, which might allow man-in-the-middle attackers to spoof servers or obtain sensitive information via a crafted certificate.

The Proofpoint Insider Threat Management Agents (formerly ObserveIT Agent) for MacOS and Linux perform improper validation of the ITM Server's certificate, which enables a remote attacker to intercept and alter these communications using a man-in-the-middle attack. All versions before 7.11.1 are affected. Agents for Windows and Cloud are not affected.

ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-protocol attacks may be possible where the behavior of one protocol service may compromise the other at the application layer.

Trillian 5.1.0.19 does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate, a different vulnerability than CVE-2009-4831.

Acronis True Image prior to 2021 Update 4 for Windows, Acronis True Image prior to 2021 Update 5 for Mac, Acronis Agent prior to build 26653, Acronis Cyber Protect prior to build 27009 did not implement SSL certificate validation.

Lynx does not verify that the server's certificate is signed by a trusted certification authority, which allows man-in-the-middle attackers to spoof SSL servers via a crafted certificate, related to improper use of a certain GnuTLS function.

Multiple vulnerabilities in Cisco Data Center Network Manager (DCNM) could allow an attacker to spoof a trusted host or construct a man-in-the-middle attack to extract sensitive information or alter certain API requests. These vulnerabilities are due to insufficient certificate validation when establishing HTTPS requests with the affected device. For more information about these vulnerabilities, see the Details section of this advisory.

In versions 3.0.0-3.5.0, 2.0.0-2.9.0, and 1.0.1, when users run the command displayed in NGINX Controller user interface (UI) to fetch the agent installer, the server TLS certificate is not verified.

iSM client versions from V5.1 prior to V12.1 running on NEC Storage Manager or NEC Storage Manager Express does not verify a server certificate properly, which allows a man-in-the-middle attacker to eavesdrop on an encrypted communication or alter the communication via a crafted certificate.

When linking a Nessus scanner or agent to Tenable.io or other manager, Nessus 6.x before 6.11 does not verify the manager's TLS certificate when making the initial outgoing connection. This could allow man-in-the-middle attacks.

VMware vCenter Server (6.7 before 6.7u3, 6.6 before 6.5u3k) contains a session hijack vulnerability in the vCenter Server Appliance Management Interface update function due to a lack of certificate validation. A malicious actor with network positioning between vCenter Server and an update repository may be able to perform a session hijack when the vCenter Server Appliance Management Interface is used to download vCenter updates.

A vulnerability in the SSL implementation of the Cisco Intelligent Proximity solution could allow an unauthenticated, remote attacker to view or alter information shared on Cisco Webex video devices and Cisco collaboration endpoints if the products meet the conditions described in the Vulnerable Products section. The vulnerability is due to a lack of validation of the SSL server certificate received when establishing a connection to a Cisco Webex video device or a Cisco collaboration endpoint. An attacker could exploit this vulnerability by using man in the middle (MITM) techniques to intercept the traffic between the affected client and an endpoint, and then using a forged certificate to impersonate the endpoint. Depending on the configuration of the endpoint, an exploit could allow the attacker to view presentation content shared on it, modify any content being presented by the victim, or have access to call controls. This vulnerability does not affect cloud registered collaboration endpoints.

A TLS certificate validation flaw was found in Elastic APM agent for Ruby versions before 2.9.0. When specifying a trusted server CA certificate via the 'server_ca_cert' setting, the Ruby agent would not properly verify the certificate returned by the APM server. This could result in a man in the middle style attack against the Ruby agent.