Oracle MySQL before 5.7.3, Oracle MySQL Connector/C (aka libmysqlclient) before 6.1.3, and MariaDB before 5.5.44 use the --ssl option to mean that SSL is optional, which allows man-in-the-middle attackers to spoof servers via a cleartext-downgrade attack, aka a "BACKRONYM" attack.

It was discovered that rpm-ostree and rpm-ostree-client before 2017.3 fail to properly check GPG signatures on packages when doing layering. Packages with unsigned or badly signed content could fail to be rejected as expected. This issue is partially mitigated on RHEL Atomic Host, where certificate pinning is used by default.

Restkit allows man-in-the-middle attackers to spoof TLS servers by leveraging use of the ssl.wrap_socket function in Python with the default CERT_NONE value for the cert_reqs argument.

rhnreg_ks in Red Hat Network Client Tools (aka rhn-client-tools) on Red Hat Gluster Storage 2.1 and Enterprise Linux (RHEL) 5, 6, and 7 does not properly validate hostnames in X.509 certificates from SSL servers, which allows remote attackers to prevent system registration via a man-in-the-middle attack.

HashiCorp Vault and Vault Enterprise 1.5.1 and newer, under certain circumstances, may exclude revoked but unexpired certificates from the CRL. Fixed in 1.5.8, 1.6.4, and 1.7.1.

The esets_daemon service in ESET Endpoint Antivirus for macOS before 6.4.168.0 and Endpoint Security for macOS before 6.4.168.0 does not properly verify X.509 certificates from the edf.eset.com SSL server, which allows man-in-the-middle attackers to spoof this server and provide crafted responses to license activation requests via a self-signed certificate. NOTE: this issue can be combined with CVE-2016-0718 to execute arbitrary code remotely as root.

Certain NETGEAR devices are affected by Missing SSL Certificate Validation. This affects R7000 1.0.9.6_1.2.19 through 1.0.11.100_10.2.10, and possibly R6120, R7800, R6220, R8000, R6350, R9000, R6400, RAX120, R6400v2, RBR20, R6800, XR300, R6850, XR500, and R7000P.

NixOS 17.03 and earlier has an unintended default absence of SSL Certificate Validation for LDAP. The users.ldap NixOS module implements user authentication against LDAP servers via a PAM module. It was found that if TLS is enabled to connect to the LDAP server with users.ldap.useTLS, peer verification will be unconditionally disabled in /etc/ldap.conf.

vdsm: certificate generation upon node creation allowing vdsm to start and serve requests from anyone who has a matching key (and certificate)

The mechanism which performs certificate validation was discovered to have a flaw that resulted in certificates signed by an internal certificate authority to not be properly validated. This issue only affects clients that are configured to utilize Tenable.sc as the vulnerability data source.

The RSS application on THOMSON THT741FTA 2.2.1 and Philips DTR3502BFTA DVB-T2 2.2.1 set-top boxes doesn't validate the SSL certificates of RSS servers, which allows a man-in-the-middle attacker to modify the data delivered to the client.

When performing add-on updates, certificate chains terminating in non-built-in-roots were rejected (even if they were legitimately added by an administrator.) This could have caused add-ons to become out-of-date silently without notification to the user. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.

Nextcloud Desktop Client before 3.3.1 is vulnerable to improper certificate validation due to lack of SSL certificate verification when using the "Register with a Provider" flow.

vdsm and vdsclient does not validate certficate hostname from another vdsm which could facilitate a man-in-the-middle attack

When using an OCSP responder Apache Tomcat Native 1.2.0 to 1.2.16 and 1.1.23 to 1.1.34 did not correctly handle invalid responses. This allowed for revoked client certificates to be incorrectly identified. It was therefore possible for users to authenticate with revoked certificates when using mutual TLS. Users not using OCSP checks are not affected by this vulnerability.

ovirt-engine-sdk-python before 3.4.0.7 and 3.5.0.4 does not verify that the hostname of the remote endpoint matches the Common Name (CN) or subjectAltName as specified by its x.509 certificate in a TLS/SSL session. This could allow man-in-the-middle attackers to spoof remote endpoints via an arbitrary valid certificate.

Nimble is a package manager for the Nim programming language. In Nim release versions before versions 1.2.10 and 1.4.4, "nimble refresh" fetches a list of Nimble packages over HTTPS by default. In case of error it falls back to a non-TLS URL http://irclogs.nim-lang.org/packages.json. An attacker able to perform MitM can deliver a modified package list containing malicious software packages. If the packages are installed and used the attack escalates to untrusted code execution.

The libwww-perl LWP::Protocol::https module 6.04 through 6.06 for Perl, when using IO::Socket::SSL as the SSL socket class, allows attackers to disable server certificate validation via the (1) HTTPS_CA_DIR or (2) HTTPS_CA_FILE environment variable.

In fence-agents before 4.0.17 does not verify remote SSL certificates in the fence_cisco_ucs.py script which can potentially allow for man-in-the-middle attackers to spoof SSL servers via arbitrary SSL certificates.

The vulnerability have been reported to affect earlier versions of Helpdesk. If exploited, this improper certificate validation vulnerability could allow an attacker to spoof a trusted entity by interfering in the communication path between the host and client. QNAP has already fixed the issue in Helpdesk 3.0.3 and later.

When parsing the AIA-Extension field of a client certificate, Apache Tomcat Native Connector 1.2.0 to 1.2.14 and 1.1.23 to 1.1.34 did not correctly handle fields longer than 127 bytes. The result of the parsing error was to skip the OCSP check. It was therefore possible for client certificates that should have been rejected (if the OCSP check had been made) to be accepted. Users not using OCSP checks are not affected by this vulnerability.

HTTPSConnections in OpenStack Keystone 2013, OpenStack Compute 2013.1, and possibly other OpenStack components, fail to validate server-side SSL certificates.

Prior to v 7.6, the Install Norton Security (INS) product can be susceptible to a certificate spoofing vulnerability, which is a type of attack whereby a maliciously procured certificate binds the public key of an attacker to the domain name of the target.

An Improper Certificate Validation on UniFi OS devices, with Identity Enterprise configured, could allow a malicious actor to execute a man-in-the-middle (MitM) attack during application update.

A certificate parsing issue was addressed with improved checks. This issue is fixed in tvOS 15.5, iOS 15.5 and iPadOS 15.5, Security Update 2022-004 Catalina, watchOS 8.6, macOS Big Sur 11.6.6, macOS Monterey 12.4. A malicious app may be able to bypass signature validation.

In Mellium mellium.im/xmpp through 0.21.0, an attacker capable of spoofing DNS TXT records can redirect a WebSocket connection request to a server under their control without causing TLS certificate verification to fail. This occurs because the wrong host name is selected during this verification.

In wolfSSL before 5.2.0, certificate validation may be bypassed during attempted authentication by a TLS 1.3 client to a TLS 1.3 server. This occurs when the sig_algo field differs between the certificate_verify message and the certificate message.

Nessus AMI versions 8.12.0 and earlier were found to either not validate, or incorrectly validate, a certificate which could allow an attacker to spoof a trusted entity by using a man-in-the-middle (MITM) attack.

IBM Security Secret Server prior to 10.9 could allow an attacker to bypass SSL security due to improper certificate validation. IBM X-Force ID: 178180.

An issue was discovered in Arm Mbed TLS before 2.24.0. It incorrectly uses a revocationDate check when deciding whether to honor certificate revocation via a CRL. In some situations, an attacker can exploit this by changing the local clock.

Cisco IronPort Web Security Appliance does not check for certificate revocation which could lead to MITM attacks

Mailvelope prior to 3.3.0 accepts or operates with invalid PGP public keys: Mailvelope allows importing keys that contain users without a valid self-certification. Keys that are obviously invalid are not rejected during import. An attacker that is able to get a victim to import a manipulated key could claim to have signed a message that originates from another person.

An issue existed in the handling of S-MIME certificates. This issue was addressed with improved validation of S-MIME certificates. This issue is fixed in macOS Mojave 10.14.4, Security Update 2019-002 High Sierra, Security Update 2019-002 Sierra. Processing a maliciously crafted mail message may lead to S/MIME signature spoofing.

Clustered Data ONTAP versions 9.0 and higher do not enforce hostname verification under certain circumstances making them susceptible to impersonation via man-in-the-middle attacks.

PostgreSQL 8.4.x before 8.4.11, 9.0.x before 9.0.7, and 9.1.x before 9.1.3 truncates the common name to only 32 characters when verifying SSL certificates, which allows remote attackers to spoof connections when the host name is exactly 32 characters.

Jenkins Proxmox Plugin 0.6.0 and earlier disables SSL/TLS certificate validation globally for the Jenkins controller JVM when configured to ignore SSL/TLS issues.

Man-in-the-middle vulnerability in Micro Focus Self Service Password Reset, affecting all versions prior to 4.4.0.4. The vulnerability could exploit invalid certificate validation and may result in a man-in-the-middle attack.

OSS Http Request (Apache Cordova Plugin) 6 is affected by: Missing SSL certificate validation. The impact is: certificate spoofing. The component is: use this library when https communication. The attack vector is: certificate spoofing.

OWASP Zed Attack Proxy (ZAP) through w2022-03-21 does not verify the TLS certificate chain of an HTTPS server.

Apache Tomcat Native 1.2.0 to 1.2.16 and 1.1.23 to 1.1.34 has a flaw that does not properly check OCSP pre-produced responses, which are lists (multiple entries) of certificate statuses. Subsequently, revoked client certificates may not be properly identified, allowing for users to authenticate with revoked certificates to connections that require mutual TLS. Users not using OCSP checks are not affected by this vulnerability.

An issue was discovered in certain Apple products. iOS before 11.2.5 is affected. macOS before 10.13.3 is affected. tvOS before 11.2.5 is affected. watchOS before 4.2.2 is affected. The issue involves the "Security" component. It allows remote attackers to spoof certificate validation via crafted name constraints.

A flaw in Mozilla's embedded certificate code might allow web sites to install root certificates on devices without user approval.

The function `OCSP_basic_verify` verifies the signer certificate on an OCSP response. In the case where the (non-default) flag OCSP_NOCHECKS is used then the response will be positive (meaning a successful verification) even in the case where the response signing certificate fails to verify. It is anticipated that most users of `OCSP_basic_verify` will not use the OCSP_NOCHECKS flag. In this case the `OCSP_basic_verify` function will return a negative value (indicating a fatal error) in the case of a certificate verification failure. The normal expected return value in this case would be 0. This issue also impacts the command line OpenSSL "ocsp" application. When verifying an ocsp response with the "-no_cert_checks" option the command line application will report that the verification is successful even though it has in fact failed. In this case the incorrect successful response will also be accompanied by error messages showing the failure and contradicting the apparently successful result. Fixed in OpenSSL 3.0.3 (Affected 3.0.0,3.0.1,3.0.2).

On 2N Access Unit 2.0 2.31.0.40.5 devices, an attacker can pose as the web relay for a man-in-the-middle attack.

Emissary-Ingress (formerly Ambassador API Gateway) through 1.13.9 allows attackers to bypass client certificate requirements (i.e., mTLS cert_required) on backend upstreams when more than one TLSContext is defined and at least one configuration exists that does not require client certificate authentication. The attacker must send an SNI specifying an unprotected backend and an HTTP Host header specifying a protected backend. (2.x versions are unaffected. 1.x versions are unaffected with certain configuration settings involving prune_unreachable_routes and a wildcard Host resource.)

jxbrowser in TI Code Composer Studio IDE 8.x through 10.x before 10.1.1 does not verify X.509 certificates for HTTPS.

A certificate validation issue was addressed. This issue is fixed in iOS 14.5 and iPadOS 14.5. An attacker in a privileged network position may be able to alter network traffic.

There is Missing SSL Certificate Validation in the Trend Micro Enterprise Mobile Security Android Application before 9.7.1193, aka VRTS-398.