Invalid RSA PKCS#1 v1.5 Signatures Vulnerability in jsrsasign
Summary
GHSA-h87q-g2wp-47pj: Signatures are mistakenly recognized to be valid in jsrsasign. Affects jsrsasign versions < 10.2.0. Fixed in 10.2.0. How to fix ↓
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Background
jsrsasign is a Node.js package that provides a JavaScript implementation of various cryptographic functions and standards. It is commonly used for generating and verifying digital signatures, encrypting and decrypting data, and working with X.509 certificates. The package is widely adopted in applications that require secure communication and authentication. However, a vulnerability has been discovered in versions prior to 10.2.0 that mistakenly recognizes some invalid RSA PKCS#1 v1.5 signatures as valid.
Vulnerability Detail
The vulnerability in jsrsasign allows for the acceptance of invalid RSA PKCS#1 v1.5 signatures as valid. This means that an attacker could potentially create a malicious signature that is incorrectly recognized as authentic, leading to various security issues. While there are no known practical attacks exploiting this vulnerability, it still poses a risk to the integrity and authenticity of cryptographic operations relying on RSA PKCS#1 v1.5 signatures.
How To Fix
Latest published version: 11.1.5 as of 23 Oct 2026
npm install jsrsasign@11.1.5Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
10.2.0
This is the first release that contains the fix.
npm install jsrsasign@10.2.0Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There is no known workaround for this vulnerability. It is essential to update to the fixed version of the package to mitigate the risk.
Conclusion
The vulnerability in jsrsasign that allows for the acceptance of invalid RSA PKCS#1 v1.5 signatures as valid poses a risk to the integrity and authenticity of cryptographic operations. It is crucial to update the package to version 10.2.0 or later to mitigate this vulnerability. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
jsrsasign is a Node.js package that provides a JavaScript implementation of various cryptographic functions and standards. It is commonly used for generating and verifying digital signatures, encrypting and decrypting data, and working with X.509 certificates.
The vulnerability allows for the acceptance of invalid RSA PKCS#1 v1.5 signatures as valid, potentially compromising the integrity and authenticity of cryptographic operations relying on such signatures.
No, there are no known practical attacks exploiting this vulnerability at the moment.
To fix this vulnerability, update the jsrsasign package to version 10.2.0 or later.
No, there is no known workaround. Updating to the fixed version is the recommended solution.
References
Related vulnerabilities
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