CVE-2021-43666 Denial of service in n/a
An attacker can cause a denial of service in mbed TLS by providing an empty password to the PKCS#12 derivation function.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-43666?
CVE-2021-43666 is a high-severity denial of service vulnerability in Arm Mbed Tls, published on 24 Mar 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls_pkcs12_derivation function when an input password's length is 0.
Weakness: CWE-130
Which versions are affected by CVE-2021-43666?
It affects 2 products.
Products include Arm Mbed Tls, Debian Debian Linux.
How do I fix CVE-2021-43666?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-43666 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-43666 exists.
Other vulnerabilities in Arm Mbed Tls
Sources
Also known as DEBIAN-CVE-2021-43666, GHSA-cgwh-hfr7-38m2, JLSEC-2025-217, UBUNTU-CVE-2021-43666.