CVE-2020-36478 Security feature bypass in n/a
Attackers can bypass certificate validation in Mbed TLS by exploiting NULL algorithm parameter handling, allowing invalid certificates to be accepted.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-36478?
CVE-2020-36478 is a high-severity vulnerability in Arm Mbed Tls, published on 23 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-295
Which versions are affected by CVE-2020-36478?
It affects 8 products.
Products include Arm Mbed Tls, Debian Debian Linux, Siemens Logo\! Cmr2020 Firmware, Siemens Logo\! Cmr2040 Firmware, Siemens Simatic Rtu3000c Firmware, Siemens Simatic Rtu3030c Firmware and 2 more.
How do I fix CVE-2020-36478?
Upgrade to a fixed version.
Is CVE-2020-36478 being exploited?
There is no known exploitation of CVE-2020-36478 in the wild and no public exploit code.
Other vulnerabilities in Arm Mbed Tls
Sources
Also known as DEBIAN-CVE-2020-36478, GHSA-8xrj-2854-7x44, JLSEC-2025-213, UBUNTU-CVE-2020-36478.