CVE-2020-36478
CVSS v3
7.5
HIGH
EPSS Score
1.1 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
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.
Technical details
- Published
- 2021-08-23
Frequently asked questions
What is 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.
Is CVE-2020-36478 actively exploited?
Active exploitation of CVE-2020-36478 has not been confirmed. Its EPSS score was 1.1% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2020-36478?
CVE-2020-36478 has a CVSS v3 base score of 7.5 (HIGH severity).
Is CVE-2020-36478 affecting your environment?
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