Vulnerability in Arm Mbed TLS

CVE-2020-36478

An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.

Vulnerability class: Improper Certificate Validation

EPSS: 0.012 (64.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2020-36478?
CVE-2020-36478 is a high-severity vulnerability in Arm Mbed TLS, classified under Improper Certificate Validation. CVSS score: 7.5/10. Published 2021-08-23.
How severe is CVE-2020-36478?
High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2020-36478 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.