CVE-2020-36421
An issue was discovered in Arm Mbed TLS before 2.23.0. Because of a side channel in modular...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2020-36421- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-203
- Updated
- 2026-11-02
CVE List
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.
- Record
CVE-2020-36421- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-203
- Updated
- 2026-11-02
EUVDEUVD-2020-23949
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.
- Record
EUVD-2020-23949- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-4h9j-8g4q-fcfq
An issue was discovered in Arm Mbed TLS before 2.23.0. Because of a side channel in modular...
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.
- Record
GHSA-4h9j-8g4q-fcfq- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-203
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2020-36421- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
OSVDEBIAN-CVE-2020-36421
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.
- Record
DEBIAN-CVE-2020-36421- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
OSVJLSEC-2025-204
An issue was discovered in Arm Mbed TLS before 2.23.0
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.
- Record
JLSEC-2025-204- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2020-36421
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.
- Record
UBUNTU-CVE-2020-36421- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
mbedtlsDebian:12 |
before 2.16.9-0.1 | 2.16.9-0.1 |
mbedtlsDebian:13 |
before 2.16.9-0.1 | 2.16.9-0.1 |
mbedtlsDebian:14 |
before 2.16.9-0.1 | 2.16.9-0.1 |
mbedtlsDebian:10 From an advisory covering 18 CVEs |
before 2.16.9-0~deb10u1, plus listed versions 2.16.0-12.16.2-12.16.3-12.16.4-12.16.5-1 |
2.16.9-0~deb10u1 |
MbedTLS_jllJulia |
before 2.16.8+0 | 2.16.8+0 |
mbedtlsUbuntu:16.04:LTS |
All versions, plus listed versions 2.1.2-12.2.0-12.2.1-12.2.1-22.2.1-2ubuntu0.12.2.1-2ubuntu0.22.2.1-2ubuntu0.3 |
None known |
mbedtlsUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 2.5.1-1ubuntu12.6.0-12.7.0-22.8.0-12.8.0-1ubuntu0.1~esm1 |
None known |
mbedtlsUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 2.16.2-12.16.3-12.16.4-1ubuntu22.16.4-1ubuntu2+esm1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-36421 is a medium vulnerability (CVSS 5.3) in Arm Mbed Tls, published July 19, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.54%, the 75th percentile. Fixed in mbedtls 2.16.9-0.1.