{"id":"CVE-2020-20949","title":"Bleichenbacher's attack on PKCS #1 v1.5 padding for RSA in STM32 cryptographic firmware library software expansion for STM32Cube (UM1924)","summary":"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 ciph…","severity":"medium","cvss":5.9,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","cwe":["CWE-327"],"vendor":"st","product":"stm32cubef0","affected":["stm32cubef0","stm32cubef1","stm32cubef2","stm32cubef3","stm32cubef4","stm32cubef7","stm32cubeg0","stm32cubeg4","stm32cubeh7","stm32cubeide","stm32cubel0","stm32cubel1","stm32cubel4","stm32cubel4+","stm32cubel5","stm32cubemonitor","stm32cubemp1","stm32cubemx","stm32cubeprogrammer","stm32cubewb","stm32cubewl","public_key_cryptography_standards_#1 = 1.5"],"published":"2021-01-20","updated":"2026-07-05","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2020-20949","references":[{"url":"http://archiv.infsec.ethz.ch/education/fs08/secsem/bleichenbacher98.pdf","label":"cve@mitre.org"},{"url":"http://x-cube-cryptolib.com","label":"cve@mitre.org"},{"url":"https://bi-zone.medium.com/silence-will-fall-or-how-it-can-take-2-years-to-get-your-vuln-registered-e6134846f5bb","label":"cve@mitre.org"},{"url":"https://www.st.com/en/embedded-software/x-cube-cryptolib.html","label":"cve@mitre.org"},{"url":"http://archiv.infsec.ethz.ch/education/fs08/secsem/bleichenbacher98.pdf","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://st.com","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://x-cube-cryptolib.com","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://bi-zone.medium.com/silence-will-fall-or-how-it-can-take-2-years-to-get-your-vuln-registered-e6134846f5bb","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.st.com/en/embedded-software/x-cube-cryptolib.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00926,"epssPercentile":0.58976,"ingestedAt":"2026-07-05T00:59:25.798Z","slug":"CVE-2020-20949","body":"## Overview\n\nBleichenbacher'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.\n\n## Affected\n\n- `stm32cubef0`\n- `stm32cubef1`\n- `stm32cubef2`\n- `stm32cubef3`\n- `stm32cubef4`\n- `stm32cubef7`\n- `stm32cubeg0`\n- `stm32cubeg4`\n- `stm32cubeh7`\n- `stm32cubeide`\n- `stm32cubel0`\n- `stm32cubel1`\n- `stm32cubel4`\n- `stm32cubel4+`\n- `stm32cubel5`\n- `stm32cubemonitor`\n- `stm32cubemp1`\n- `stm32cubemx`\n- `stm32cubeprogrammer`\n- `stm32cubewb`\n- `stm32cubewl`\n- `public_key_cryptography_standards_#1 = 1.5`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":33,"depthScoreParts":{"impact":32.5,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}