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-DEBIAN12-MBEDTLS-1569100
  • 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:12 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:12 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