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Critical

RSA signature validation vulnerability on maleable encoded message in jsrsasign

  • Disclosed: 16.04.2021
  • Updated: 11.10.2026 10:22

Impact

Vulnerable jsrsasign will accept RSA signature with improper PKCS#1.5 padding. Decoded RSA signature value consists following form: 01(ff...(8 or more ffs)...ff)00[ASN.1 OF DigestInfo] Its byte length must be the same as RSA key length, however such checking was not sufficient.

To make crafted message for practical attack is very hard.

Patches

Users validating RSA signature should upgrade to 10.2.0 or later.

Workarounds

There is no workaround. Not to use RSA signature validation in jsrsasign.

ACKNOWLEDGEMENT

Thanks to Daniel Yahyazadeh @yahyazadeh for reporting and analyzing this vulnerability.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package jsrsasign < 10.2.0 10.2.0

References

CVSS score 9.1/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE)
CWE-347
Platform
npm
Package
jsrsasign
Disclosed
16.04.2021
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-27fj-mc8w-j9wg - CC BY 4.0

Vulnerability history: jsrsasign

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (14) in the archive
Total entries
14
First → latest
06.2020 03.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 4
  • High 7
  • Medium 2
  • Low 1

Disclosures per year

Severity:
  1. jsrsasign: DSA signatures or X.509 certificates can be forged via DSA domain-parameter validation in KJUR.crypto.DSA.setPublic
    High · 7.4 CVE-2026-4600 < 11.1.1 11.1.1
  2. jsrsasign: Negative Exponent Handling Leads to Signature Verification Bypass
    High · 7.5 CVE-2026-4602 < 11.1.1 11.1.1
  3. jsrsasign: Incomplete Comparison Allows DSA Private Key Recovery via Biased Nonce Generation
    Critical · 9.1 CVE-2026-4599 >= 7.0.0, < 11.1.1 11.1.1
  4. jsrsasign is vulnerable to DoS through Infinite Loop when processing zero or negative inputs
    High · 7.5 CVE-2026-4598 < 11.1.1 11.1.1
  5. jsrsasign: Missing cryptographic validation during DSA signing enables private key extraction
    High · 8.7 CVE-2026-4601 < 11.1.1 11.1.1
  6. Marvin Attack of RSA and RSAOAEP decryption in jsrsasign
    High · 7.5 CVE-2024-21484 < 11.0.0 11.0.0
  7. JWS and JWT signature validation vulnerability with special characters
    High · 8.6 CVE-2022-25898 >= 4.8.0, < 10.5.25 10.5.25
  8. RSA signature validation vulnerability on maleable encoded message in jsrsasign this entry
    Critical · 9.1 CVE-2021-30246 < 10.2.0 10.2.0
  9. ECDSA signature validation vulnerability by accepting wrong ASN.1 encoding in jsrsasign
    High · 7.5 CVE-2020-14966 >= 4.0.0, < 8.0.19 8.0.19
  10. RSA PKCS#1 decryption vulnerability with prepending zeros in jsrsasign
    Critical · 9.8 CVE-2020-14967 < 8.0.18 8.0.18
  11. RSA-PSS signature validation vulnerability by prepending zeros in jsrsasign
    Critical · 9.8 CVE-2020-14968 >= 3.0.0, < 8.0.17 8.0.17

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