An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. The X.509 certificate validation can be skipped for a TLS-based e-mail server.

The functions to fetch e-mail via POP3 or IMAP as well as sending e-mail via SMTP use OpenSSL for static SSL or TLS based communication. As the SSL_get_verify_result() function is not used the certificated is trusted always and it can not be ensured that the certificate satisfies all necessary security requirements. This could allow an attacker to use an invalid certificate to claim to be a trusted host, use expired certificates, or conduct other attacks that could be detected if the certificate is properly validated. This issue affects OTRS: from 7.0.X before 7.0.47, from 8.0.X before 8.0.37; ((OTRS)) Community Edition: from 6.0.X through 6.0.34.

Precision Bridge PrecisionBridge.exe (aka the thick client) before 7.3.21 allows an integrity violation in which the same license key is used on multiple systems, via vectors involving a Process Hacker memory dump, error message inspection, and modification of a MAC address.

Improper certificate validation in Zoom Workplace for Linux before version 6.4.13 may allow an unauthorized user to conduct an information disclosure via network access.

WP-CLI is the command-line interface for WordPress. An improper error handling in HTTPS requests management in WP-CLI version 0.12.0 and later allows remote attackers able to intercept the communication to remotely disable the certificate verification on WP-CLI side, gaining full control over the communication content, including the ability to impersonate update servers and push malicious updates towards WordPress instances controlled by the vulnerable WP-CLI agent, or push malicious updates toward WP-CLI itself. The vulnerability stems from the fact that the default behavior of `WP_CLI\Utils\http_request()` when encountering a TLS handshake error is to disable certificate validation and retry the same request. The default behavior has been changed with version 2.5.0 of WP-CLI and the `wp-cli/wp-cli` framework (via https://github.com/wp-cli/wp-cli/pull/5523) so that the `WP_CLI\Utils\http_request()` method accepts an `$insecure` option that is `false` by default and consequently that a TLS handshake failure is a hard error by default. This new default is a breaking change and ripples through to all consumers of `WP_CLI\Utils\http_request()`, including those in separate WP-CLI bundled or third-party packages. https://github.com/wp-cli/wp-cli/pull/5523 has also added an `--insecure` flag to the `cli update` command to counter this breaking change. There is no direct workaround for the default insecure behavior of `wp-cli/wp-cli` versions before 2.5.0. The workaround for dealing with the breaking change in the commands directly affected by the new secure default behavior is to add the `--insecure` flag to manually opt-in to the previous insecure behavior.

The client applications in 3CX on Windows, the 3CX app for iOS, and the 3CX application for Android through 2022-03-17 lack SSL certificate validation.

Incorrect validation of the TLS SNI hostname in osquery versions after 2.9.0 and before 4.2.0 could allow an attacker to MITM osquery traffic in the absence of a configured root chain of trust.