{"cve":"CVE-2021-36647","nvd":{"published":"2023-01-17T21:15:10.880","modified":"2026-06-17T03:58:59.387","status":"Modified","description":"Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N","score":4.7},"cwes":["CWE-327"],"references":["https://github.com/ARMmbed/mbedtls/releases/","https://kouzili.com/Load-Step.pdf","https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2021-07-1","https://github.com/ARMmbed/mbedtls/releases/","https://kouzili.com/Load-Step.pdf"],"products":["arm:mbed_tls","trustedfirmware:mbed_tls"],"source":"nvd","synced_at":"2026-10-19T21:37:34.931465858+00:00"},"epss":{"cve":"CVE-2021-36647","score":0.00172,"percentile":0.06557,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}