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Published: 23 August 2021

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).



CVSS 3 base score: 5.9


Package Release Status
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Needs triage

hirsute Ignored
(reached end-of-life)
impish Needs triage

jammy Needs triage

trusty Does not exist

upstream Needs triage

xenial Ignored
(out of standard support)