CVE-2021-30246Public exploit

Signature acceptance via lenient PKCS#1 padding parsing

Published Apr 7, 2021 · Updated Aug 3, 2024

Improper RSA signature verification in jsrsasign for Node.js 10.1.13 and earlier allows attackers to have malformed signatures accepted as valid. RSAKey.prototype.verify strips the decoded message prefix with an incorrect regular expression without enforcing the leading byte, block type, or minimum padding length. Constructing a practical forgery still depends on a hash collision, and no practical attack is known.

CVSS severity9.1
Critical
EPSS probability0.96%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper RSA signature verification in jsrsasign for Node.js 10.1.13 and earlier allows attackers to have malformed signatures accepted as valid. RSAKey.prototype.verify strips the decoded message prefix with an incorrect regular expression without enforcing the leading byte, block type, or minimum padding length. Constructing a practical forgery still depends on a hash collision, and no practical attack is known.

The record

CVE
CVE-2021-30246
Published
Apr 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Apr 7, 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 vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.1GitLab Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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.

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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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature

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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