CVE-2020-36477
Published: 23 August 2021
Summary
CVE-2020-36477 is a medium-severity Improper Certificate Validation (CWE-295) vulnerability in Arm Mbed Tls. Its CVSS base score is 5.9 (Medium).
Operationally, ranked at the 32.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2020-23963
Vulnerability details
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…
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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).
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
When certificates are used to establish component provenance, the control requires correct certificate validation procedures.
Mandates approved trust anchors and issuance policies, directly preventing acceptance of unvalidated or untrusted certificates.
Correct system time is required for proper enforcement of certificate notBefore/notAfter dates and time-based revocation checks.