PT-2021-6718 · Arm+2 · Mbed Tls+2

Hyesoon Kim + 6 · CVE-2020-36421 · Published 2020-07-02 · Updated 2025-12-03

Positive Technologies (AI Summary)

CVSS v3.1

5.3

Medium

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Name of the Vulnerable Software and Affected Versions Arm Mbed TLS versions prior to 2.23.0

Description The issue is related to a side channel in modular exponentiation, which could disclose an RSA private key used in a secure enclave. This is due to a dependency of the instruction timing on the instruction data, allowing a remote attacker to access confidential data.

Recommendations For versions prior to 2.23.0, update to version 2.23.0 or later to resolve the issue. As a temporary workaround, consider restricting access to sensitive data handled by the secure enclave until the update is applied.

Exploit

Fix

Side Channel Attack

Weakness Enumeration

CWE-203

Related Identifiers

ALT-PU-2020-2262

ALT-PU-2020-2355

BDU:2022-02083

CVE-2020-36421

DLA-3249-1

Affected Products

Alt Linux

Astra Linux

Mbed Tls

References · 18

• 🔥 https://github.com/ARMmbed/mbedtls/issues/3394 · Exploit
• https://cve.org/CVERecord?id=CVE-2020-36421 · Security Note
• https://bdu.fstec.ru/vul/2022-02083 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2020-36421 · Vendor Advisory
• https://ubuntu.com/security/CVE-2020-36421 · Vendor Advisory
• https://bugs.gentoo.org/730752 · Patch
• https://nvd.nist.gov/vuln/detail/CVE-2020-36421 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2020-36421 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2020-36421 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2020-36421 · Vendor Advisory
• https://osv.dev/vulnerability/DLA-3249-1 · Vendor Advisory
• https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.7 · Note
• https://github.com/ARMmbed/mbedtls/releases/tag/v2.23.0 · Note
• https://github.com/ARMmbed/mbedtls/pull/3398 · Note
• https://t.me/cvenotify/40671 · Telegram Post