Vulnerability in Arm Mbed TLS
CVE-2020-36477
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).
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.009 (57.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.009 · change: +0.000
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/ARMmbed/mbedtls/releases/tag/v2.24.0 (Third Party Advisory, Release Notes)
- github.com/ARMmbed/mbedtls/issues/3498 (Third Party Advisory)
- security.gentoo.org/glsa/202301-08 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2020-36477?
- CVE-2020-36477 is a medium-severity vulnerability in Arm Mbed TLS, classified under Improper Certificate Validation. CVSS score: 5.9/10. Published 2021-08-23.
- How severe is CVE-2020-36477?
- Medium severity. CVSS v3 base score is 5.9 out of 10.
- Is CVE-2020-36477 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.