CVE-2020-20949: IETF Public Key Cryptography Standards #1

Medium severity, CVSS 5.9. EPSS: 0.9% chance of exploitation in the next 30 days.

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.

Affected products

• IETF Public Key Cryptography Standards #1: version 1.5 only
• St STM32CUBEF0: affected versions not specified
• St STM32CUBEF1: affected versions not specified
• St STM32CUBEF2: affected versions not specified
• St STM32CUBEF3: affected versions not specified
• St STM32CUBEF4: affected versions not specified
• St STM32CUBEF7: affected versions not specified
• St STM32CUBEG0: affected versions not specified
• St STM32CUBEG4: affected versions not specified
• St STM32CUBEH7: affected versions not specified
• St STM32CUBEIDE: affected versions not specified
• St STM32CUBEL0: affected versions not specified
• St STM32CUBEL1: affected versions not specified
• St STM32CUBEL4: affected versions not specified
• St STM32CUBEL4+: affected versions not specified
• St STM32CUBEL5: affected versions not specified
• St STM32CUBEMONITOR: affected versions not specified
• St STM32CUBEMP1: affected versions not specified
• St STM32CUBEMX: affected versions not specified
• St STM32CUBEPROGRAMMER: affected versions not specified
• St STM32CUBEWB: affected versions not specified
• St STM32CUBEWL: affected versions not specified

Published 2021-01-20. Last modified 2026-07-09.