What’s Vulnerable › Vulnerabilities

CVE-2020-36421

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-07-19 · updated 2026-06-17
• Weakness: CWE-203

Description

An issue was discovered in Arm Mbed TLS before 2.23.0. Because of a side channel in modular exponentiation, an RSA private key used in a secure enclave could be disclosed.

Affected products

• mbedtls: before 2.16.7; from 2.17.0 before 2.23.0 — fixed in 2.16.7, 2.23.0
• Debian Linux: 10.0

How to fix

Upgrade to a fixed version: mbedtls 2.16.7, 2.23.0. Check the vendor advisory for mitigations.

References

• https://bugs.gentoo.org/730752
• https://github.com/ARMmbed/mbedtls/issues/3394
• https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.7
• https://github.com/ARMmbed/mbedtls/releases/tag/v2.23.0
• https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html
• https://bugs.gentoo.org/730752
• https://github.com/ARMmbed/mbedtls/issues/3394
• https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.7
• https://github.com/ARMmbed/mbedtls/releases/tag/v2.23.0
• https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html

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