Improper Certificate Validation Affecting mbedtls package, versions <2.28.0-0.3


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.12% (47th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-MBEDTLS-1569093
  • published24 Aug 2021
  • disclosed23 Aug 2021

Introduced: 23 Aug 2021

CVE-2020-36477  (opens in a new tab)
CWE-295  (opens in a new tab)

How to fix?

Upgrade Debian:unstable mbedtls to version 2.28.0-0.3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream mbedtls package and not the mbedtls package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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 Scores

version 3.1