CVE-2020-20949 Weak cryptography in n/a

Medium 5.9 Published 20 Jan 2021 Updated 9 Jul 2026

Attackers can decrypt RSA ciphertexts via Bleichenbacher's oracle attack on STM32Cube firmware, leading to remote information disclosure.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2020-20949?

CVE-2020-20949 is a medium-severity vulnerability in n/a, published on 20 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Bleichenbacher's attack on PKCS #1 v1.5 padding for RSA in STM32 cryptographic firmware library software expansion for STM32Cube (UM1924). The vulnerability can allow one to use Bleichenbacher's oracle attack to decrypt an encrypted ciphertext by making successive queries to the server using the vulnerable library, resulting in remote information disclosure.

Weakness: CWE-327

Which versions are affected by CVE-2020-20949?

It affects 22 products.

Products include Ietf Public Key Cryptography Standards \#1, St Stm32cubef0, St Stm32cubef1, St Stm32cubef2, St Stm32cubef3, St Stm32cubef4 and 16 more.

How do I fix CVE-2020-20949?

No fix has been published for CVE-2020-20949 yet. Limit exposure of the affected software until one is available.

Is CVE-2020-20949 being exploited?

There is no known exploitation of CVE-2020-20949 in the wild and no public exploit code.

CVE-2020-20950 Weak cryptography in n/a Medium 5.9

Sources

Also known as GHSA-7p98-xcgc-gwhj.