CVE-2020-14966Public exploitNetwork attack vector

Signature-policy bypass via noncanonical ASN.1 encoding

Published Jun 22, 2020 · Updated Aug 4, 2024

Improper ECDSA signature verification in jsrsasign 4.0.0 through 8.0.18 allows remote attackers to bypass canonical-signature checks. The ECDSA verifier's ASN.1 DER parser accepts overlong sequence lengths, redundant zero bytes in INTEGER values, and trailing zero bytes, causing altered encodings of valid signatures to verify. Impact requires an application that validates ASN.1-encoded ECDSA signatures and depends on a single canonical signature; raw R-and-S concatenations are unaffected.

CVSS severity7.5
High
EPSS probability1.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper ECDSA signature verification in jsrsasign 4.0.0 through 8.0.18 allows remote attackers to bypass canonical-signature checks. The ECDSA verifier's ASN.1 DER parser accepts overlong sequence lengths, redundant zero bytes in INTEGER values, and trailing zero bytes, causing altered encodings of valid signatures to verify. Impact requires an application that validates ASN.1-encoded ECDSA signatures and depends on a single canonical signature; raw R-and-S concatenations are unaffected.

The record

CVE
CVE-2020-14966
Published
Jun 22, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, T1553
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 22, 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

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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

5.0NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1553Subvert Trust Controls

Public exploit references

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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