CVE-2020-36477

NameCVE-2020-36477
DescriptionAn 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).
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
mbedtls (PTS)stretch2.4.2-1+deb9u3fixed
stretch (security)2.4.2-1+deb9u4fixed
buster2.16.0-1vulnerable
bullseye2.16.9-0.1vulnerable
bookworm, sid2.16.11-0.3vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
mbedtlssourceexperimental2.28.0-0.1
mbedtlssourcestretch(not affected)
mbedtlssource(unstable)(unfixed)

Notes

[stretch] - mbedtls <not-affected> (2.4 not affected)
https://github.com/ARMmbed/mbedtls/issues/3498
https://github.com/ARMmbed/mbedtls/commit/f3e4bd8632b71dc491e52e6df87dc3e409d2b869 (development)

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