CVE-2020-20949
MediumCVSS 5.9Exploitation Probability (EPSS)
Elevated risk56th percentile - higher than 56% of all known CVEs
Summary
A vulnerability in the STM32 cryptographic firmware library (UM1924) allows a Bleichenbacher attack on PKCS #1 v1.5 padding for RSA. An attacker can remotely decrypt encrypted ciphertext by making successive queries to the server using the vulnerable library.
Risk Assessment
The risk involves potential remote disclosure of confidential information transmitted in encrypted form, which could lead to data leakage or communication compromise.
Recommendation
Update the STM32 cryptographic library to a version that implements secure mechanisms (e.g., RSA-OAEP) or apply additional protections against oracle attacks.
Original NVD description (English source)
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.