CVE-2021-29415Known exploitationPublic exploit

Private-key recovery via ECDSA timing leakage

Published May 21, 2021 · Updated Aug 3, 2024

Timing side channel in Nordic Semiconductor nRF52840 through 2021-03-29 allows physically proximate attackers to recover ECDSA keys. CryptoCell 310 signature runtime correlates with the secret ECDSA nonce bit length, enabling a lattice attack after about 12,000 timing observations. Physical possession for about half a day and repeated signatures are required; only keys used directly for ECDSA are exposed.

CVSS severity5.5
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Timing side channel in Nordic Semiconductor nRF52840 through 2021-03-29 allows physically proximate attackers to recover ECDSA keys. CryptoCell 310 signature runtime correlates with the secret ECDSA nonce bit length, enabling a lattice attack after about 12,000 timing observations. Physical possession for about half a day and repeated signatures are required; only keys used directly for ECDSA are exposed.

The record

CVE
CVE-2021-29415
Published
May 21, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-203, T1552.004
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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 vectorphysical
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

2.1NIST National Vulnerability DatabaseAV:L/AC:L/Au:N/C:P/I:N/A:N
5.5NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-203Observable Discrepancy
T1552.004Unsecured Credentials: Private Keys

Public exploit references

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

Reported exploitation

Technologies

Your stack

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Your stack

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