NetworkManager 0.9 and earlier allows local users to use other users' certificates or private keys when making a connection via the file path when adding a new connection.

software-properties was vulnerable to a person-in-the-middle attack due to incorrect TLS certificate validation in softwareproperties/ppa.py. software-properties didn't check TLS certificates under python2 and only checked certificates under python3 if a valid certificate bundle was provided. Fixed in software-properties version 0.92.

Node.js < 12.22.9, < 14.18.3, < 16.13.2, and < 17.3.1 did not handle multi-value Relative Distinguished Names correctly. Attackers could craft certificate subjects containing a single-value Relative Distinguished Name that would be interpreted as a multi-value Relative Distinguished Name, for example, in order to inject a Common Name that would allow bypassing the certificate subject verification.Affected versions of Node.js that do not accept multi-value Relative Distinguished Names and are thus not vulnerable to such attacks themselves. However, third-party code that uses node's ambiguous presentation of certificate subjects may be vulnerable.

Mozilla Firefox prior to 3.6 has a DoS vulnerability due to an issue in the validation of certificates.

dirmngr before 2.1.0 improperly handles certain system calls, which allows remote attackers to cause a denial of service (DOS) via a specially-crafted certificate.

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.

offlineimap before 6.3.4 added support for SSL server certificate validation but it is still possible to use SSL v2 protocol, which is a flawed protocol with multiple security deficiencies.

offlineimap before 6.3.2 does not check for SSL server certificate validation when "ssl = yes" option is specified which can allow man-in-the-middle attacks.

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 TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft Internet Information Services (IIS) 7.0, mod_ssl in the Apache HTTP Server 2.2.14 and earlier, OpenSSL before 0.9.8l, GnuTLS 2.8.5 and earlier, Mozilla Network Security Services (NSS) 3.12.4 and earlier, multiple Cisco products, and other products, does not properly associate renegotiation handshakes with an existing connection, which allows man-in-the-middle attackers to insert data into HTTPS sessions, and possibly other types of sessions protected by TLS or SSL, by sending an unauthenticated request that is processed retroactively by a server in a post-renegotiation context, related to a "plaintext injection" attack, aka the "Project Mogul" issue.

Mozilla Network Security Services (NSS) before 3.12.3, Firefox before 3.0.13, Thunderbird before 2.0.0.23, and SeaMonkey before 1.1.18 do not properly handle a '\0' character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority. NOTE: this was originally reported for Firefox before 3.5.

The Network Security Services (NSS) library before 3.12.3, as used in Firefox; GnuTLS before 2.6.4 and 2.7.4; OpenSSL 0.9.8 through 0.9.8k; and other products support MD2 with X.509 certificates, which might allow remote attackers to spoof certificates by using MD2 design flaws to generate a hash collision in less than brute-force time. NOTE: the scope of this issue is currently limited because the amount of computation required is still large.

In the client side of Heimdal before 7.6.0, failure to verify anonymous PKINIT PA-PKINIT-KX key exchange permits a man-in-the-middle attack. This issue is in krb5_init_creds_step in lib/krb5/init_creds_pw.c.

The urllib3 library before 1.24.2 for Python mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to use of the ssl_context, ca_certs, or ca_certs_dir argument.

A flaw was found in Keycloak in versions before 10.0.0, where it does not perform the TLS hostname verification while sending emails using the SMTP server. This flaw allows an attacker to perform a man-in-the-middle (MITM) attack.

OCSP revocation status of recipient certificates was not checked when sending S/Mime encrypted email, and revoked certificates would be accepted. Thunderbird versions from 68 to 102.9.1 were affected by this bug. This vulnerability affects Thunderbird < 102.10.

When TLS is enabled with ssl-endpoint-identification-enabled set to true, Apache Geode fails to perform hostname verification of the entries in the certificate SAN during the SSL handshake. This could compromise intra-cluster communication using a man-in-the-middle attack.

In Dogtag PKI through 10.8.3, the pki.client.PKIConnection class did not enable python-requests certificate validation. Since the verify parameter was hard-coded in all request functions, it was not possible to override the setting. As a result, tools making use of this class, such as the pki-server command, may have been vulnerable to Person-in-the-Middle attacks in certain non-localhost use cases. This is fixed in 10.9.0-b1.

Rakuten card App for iOS 5.2.0 through 5.2.4 does not verify SSL certificates which might allow remote attackers to execute man-in-the-middle attacks.

WeeChat (aka Wee Enhanced Environment for Chat) 3.2 to 3.4 before 3.4.1 does not properly verify the TLS certificate of the server, after certain GnuTLS options are changed, which allows man-in-the-middle attackers to spoof a TLS chat server via an arbitrary certificate. NOTE: this only affects situations where weechat.network.gnutls_ca_system or weechat.network.gnutls_ca_user is changed without a WeeChat restart.