An issue was discovered in Mbed TLS before 2.24.0. The verification of X.509 certificates when matching the expected common name (the cn argument of mbedtls_x509_crt_verify) with the actual certificate name is mishandled: when the subjecAltName extension is present, the expected name is compared to any name in that extension regardless of its type. This means that an attacker could impersonate a 4-byte or 16-byte domain by getting a certificate for the corresponding IPv4 or IPv6 address (this would require the attacker to control that IP address, though).
Weakness
The product does not validate, or incorrectly validates, a certificate.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Mbed_tls | Arm | * | 2.24.0 (excluding) |
| Mbedtls | Ubuntu | bionic | * |
| Mbedtls | Ubuntu | esm-apps/bionic | * |
| Mbedtls | Ubuntu | esm-apps/focal | * |
| Mbedtls | Ubuntu | esm-apps/xenial | * |
| Mbedtls | Ubuntu | focal | * |
| Mbedtls | Ubuntu | hirsute | * |
| Mbedtls | Ubuntu | impish | * |
| Mbedtls | Ubuntu | kinetic | * |
| Mbedtls | Ubuntu | lunar | * |
| Mbedtls | Ubuntu | mantic | * |
| Mbedtls | Ubuntu | oracular | * |
| Mbedtls | Ubuntu | trusty | * |
| Mbedtls | Ubuntu | upstream | * |
| Mbedtls | Ubuntu | xenial | * |