CVE-2020-1026Network attack vector

Key disclosure and signature forgery via ECC miscalculation

Published Apr 15, 2020 · Updated Aug 4, 2024

Security feature bypass in Microsoft MSR JavaScript Cryptography Library 1.4 lets attackers learn ECC key data or forge signatures. The ECC implementation performs erroneous arithmetic, uses an incorrect NIST P-521 curve definition, and can accept an invalid ECDSA signature. Reachability requires a consuming application to invoke affected ECC operations with attacker-influenced inputs; private-key secrecy and signature integrity are exposed.

CVSS severity9.8
Critical
EPSS probability2.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Security feature bypass in Microsoft MSR JavaScript Cryptography Library 1.4 lets attackers learn ECC key data or forge signatures. The ECC implementation performs erroneous arithmetic, uses an incorrect NIST P-521 curve definition, and can accept an invalid ECDSA signature. Reachability requires a consuming application to invoke affected ECC operations with attacker-influenced inputs; private-key secrecy and signature integrity are exposed.

The record

CVE
CVE-2020-1026
Published
Apr 15, 2020
Updated
Aug 4, 2024
Vendor
Microsoft
Product
MSR JavaScript Cryptography Library
Classifications
CWE-200, CWE-347
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2020CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · MSR JavaScript Cryptography Libraryversion=unspecified

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
CWE-347Improper Verification of Cryptographic Signature

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo