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.

LibreOffice supports digital signatures of ODF documents and macros within documents, presenting visual aids that no alteration of the document occurred since the last signing and that the signature is valid. An Improper Certificate Validation vulnerability in LibreOffice allowed an attacker to modify a digitally signed ODF document to insert an additional signing time timestamp which LibreOffice would incorrectly present as a valid signature signed at the bogus signing time. This issue affects: The Document Foundation LibreOffice 7-0 versions prior to 7.0.6; 7-1 versions prior to 7.1.2.

When AdaCore Ada Web Server 25.0.0 is linked with GnuTLS, the default behaviour of AWS.Client is vulnerable to a man-in-the-middle attack because of lack of verification of an HTTPS server's certificate (unless the using program specifies a TLS configuration).

It was found in OpenShift, before version 4.8, that the generated certificate for the in-cluster Service CA, incorrectly included additional certificates. The Service CA is automatically mounted into all pods, allowing them to safely connect to trusted in-cluster services that present certificates signed by the trusted Service CA. The incorrect inclusion of additional CAs in this certificate would allow an attacker that compromises any of the additional CAs to masquerade as a trusted in-cluster service.

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.

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.

Hammer CLI, a CLI utility for Foreman, before version 0.10.0, did not explicitly set the verify_ssl flag for apipie-bindings that disable it by default. As a result the server certificates are not checked and connections are prone to man-in-the-middle attacks.

Improper validation of certificate with host mismatch in Apache Log4j SMTP appender. This could allow an SMTPS connection to be intercepted by a man-in-the-middle attack which could leak any log messages sent through that appender. Fixed in Apache Log4j 2.12.3 and 2.13.1

A flaw was found in keycloak affecting versions 11.0.3 and 12.0.0. An expired certificate would be accepted by the direct-grant authenticator because of missing time stamp validations. The highest threat from this vulnerability is to data confidentiality and integrity.

IMAPFilter through 2.6.12 does not validate the hostname in an SSL certificate.

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.

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.