CVE-2021-36647
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…
Does this matter?
Lower severity and a low EPSS score (0.16%). Track it; it rarely justifies an emergency change on its own.
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 3.1
- 4.7 MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 0.16% probability · 6th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-327
- Affected
- arm/mbed tls · trustedfirmware/mbed tls
- Source
- cve@mitre.org
References
- https://github.com/ARMmbed/mbedtls/releases/Third Party Advisory
- https://kouzili.com/Load-Step.pdfThird Party Advisory
- https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2021-07-1Vendor Advisory
- https://github.com/ARMmbed/mbedtls/releases/Third Party Advisory
- https://kouzili.com/Load-Step.pdfThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2025/06/msg00034.html
- https://tls.mbed.org/tech-updates/security-advisories/mbedtls-security-advisory-2021-07-1Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.