CVE-2020-36422

ECC private-key recovery via unblinded scalar multiplication

Published Jul 19, 2021 · Updated Aug 4, 2024

Side-channel leakage in Arm Mbed TLS before 2.23.0 allows local users to recover ECC private keys through timing and memory observations. Affected key-loading paths and ECP multiplication functions perform scalar multiplication without internal randomization when the public key is absent or f_rng is null. Exploitation requires precise timing and memory-access data, typically from an untrusted operating system observing a secure enclave, and exposes the entire ECC private key.

CVSS severity5.3
Medium
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Side-channel leakage in Arm Mbed TLS before 2.23.0 allows local users to recover ECC private keys through timing and memory observations. Affected key-loading paths and ECP multiplication functions perform scalar multiplication without internal randomization when the public key is absent or f_rng is null. Exploitation requires precise timing and memory-access data, typically from an untrusted operating system observing a secure enclave, and exposes the entire ECC private key.

The record

CVE
CVE-2020-36422
Published
Jul 19, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-203
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Jul 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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