An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.

In GNOME grilo though 0.3.13, grl-net-wc.c does not enable TLS certificate verification on the SoupSessionAsync objects it creates, leaving users vulnerable to network MITM attacks. NOTE: this is similar to CVE-2016-20011.

In GNOME libgfbgraph through 0.2.4, gfbgraph-photo.c does not enable TLS certificate verification on the SoupSessionSync objects it creates, leaving users vulnerable to network MITM attacks. NOTE: this is similar to CVE-2016-20011.

In GNOME libgda through 6.0.0, gda-web-provider.c does not enable TLS certificate verification on the SoupSessionSync objects it creates, leaving users vulnerable to network MITM attacks. NOTE: this is similar to CVE-2016-20011.

In GNOME evolution-rss through 0.3.96, network-soup.c does not enable TLS certificate verification on the SoupSessionSync objects it creates, leaving users vulnerable to network MITM attacks. NOTE: this is similar to CVE-2016-20011.

In GNOME libzapojit through 0.0.3, zpj-skydrive.c does not enable TLS certificate verification on the SoupSessionSync objects it creates, leaving users vulnerable to network MITM attacks. NOTE: this is similar to CVE-2016-20011.

Icinga is a monitoring system which checks the availability of network resources, notifies users of outages, and generates performance data for reporting. In versions 2.5.0 through 2.13.0, ElasticsearchWriter, GelfWriter, InfluxdbWriter and Influxdb2Writer do not verify the server's certificate despite a certificate authority being specified. Icinga 2 instances which connect to any of the mentioned time series databases (TSDBs) using TLS over a spoofable infrastructure should immediately upgrade to version 2.13.1, 2.12.6, or 2.11.11 to patch the issue. Such instances should also change the credentials (if any) used by the TSDB writer feature to authenticate against the TSDB. There are no workarounds aside from upgrading.

The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server with a computer. Clients using the Nextcloud end-to-end encryption feature download the public and private key via an API endpoint. In versions prior to 3.3.0, the Nextcloud Desktop client fails to check if a private key belongs to previously downloaded public certificate. If the Nextcloud instance serves a malicious public key, the data would be encrypted for this key and thus could be accessible to a malicious actor. This issue is fixed in Nextcloud Desktop Client version 3.3.0. There are no known workarounds aside from upgrading.

If the Node.js https API was used incorrectly and "undefined" was in passed for the "rejectUnauthorized" parameter, no error was returned and connections to servers with an expired certificate would have been accepted.

The AWV component of Mitel MiCollab before 9.3 could allow an attacker to perform a Man-In-the-Middle attack due to improper TLS negotiation. A successful exploit could allow an attacker to view and modify data.