CVE-2019-20399Network attack vector

Information disclosure via data-dependent scalar comparison timing

Published Jan 22, 2020 · Updated Aug 5, 2024

Timing side channel in Parity libsecp256k1-rs before 0.3.1 allows remote attackers to infer information about processed scalars. Scalar::check_overflow uses short-circuiting Boolean comparisons across scalar limbs, making execution time depend on the scalar value. Exploitation requires repeated, precise timing observations of an exposed caller; the flaw discloses information without altering data or interrupting service.

CVSS severity5.9
Medium
EPSS probability0.88%
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 Parity libsecp256k1-rs before 0.3.1 allows remote attackers to infer information about processed scalars. Scalar::check_overflow uses short-circuiting Boolean comparisons across scalar limbs, making execution time depend on the scalar value. Exploitation requires repeated, precise timing observations of an exposed caller; the flaw discloses information without altering data or interrupting service.

The record

CVE
CVE-2019-20399
Published
Jan 22, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 22, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
4.3NIST NVDAV:N/AC:M/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
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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