CVE-2021-36647
MEDIUMDescription
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.
How to fix
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 6% of all known CVEs.
References
Related Vulnerabilities
Other CWE-327 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2015-2808 | Low | 3.7 | 74% | - | Fix |
| CVE-2023-34039 | Critical | 9.8 | 64% | - | Fix |
| CVE-2016-6602 | Critical | 9.8 | 55% | - | - |
| CVE-2014-8687 | Critical | 9.8 | 44% | - | - |
| CVE-2020-13777 | High | 7.4 | 18% | - | Fix |
| CVE-2017-17428 | Medium | 5.9 | 15% | - | - |
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Markdown
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Start freeThis product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-05.