CVE-2020-15522

Private-key disclosure via unblinded EC inversion

Published May 20, 2021 · Updated Aug 4, 2024

Timing side channel in Bouncy Castle BC Java before 1.66 and related APIs allows attackers to infer ECDSA private-key information. ECPoint normalization inverted a projective coordinate directly, so secret-dependent execution time exposed information that the patched code masks by multiplying the coordinate with a random field element before inversion. The attacker must measure multiple deterministic ECDSA signatures with sufficient timing precision; the reported consequence is private-key information disclosure, not data modification or service interruption.

CVSS severity5.1
Medium
EPSS probability1.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Timing side channel in Bouncy Castle BC Java before 1.66 and related APIs allows attackers to infer ECDSA private-key information. ECPoint normalization inverted a projective coordinate directly, so secret-dependent execution time exposed information that the patched code masks by multiplying the coordinate with a random field element before inversion. The attacker must measure multiple deterministic ECDSA signatures with sufficient timing precision; the reported consequence is private-key information disclosure, not data modification or service interruption.

The record

CVE
CVE-2020-15522
Published
May 20, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-203, CWE-362
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. May 20, 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 vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.1GitHub Advisory DatabaseCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
5.9OSVCVSS:3.1/AV:N/AC:H/PR:N/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.

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No observations available

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

Weakness, pattern, technique

CWE-203Observable Discrepancy
CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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