CVE-2026-4599: jsrsasign Critical Vulnerability in DSA Nonce Generation
Summary
CVE-2026-4599: jsrsasign: Incomplete Comparison Allows DSA Private Key Recovery via Biased Nonce Generation. Affects jsrsasign versions >= 7.0.0, < 11.1.1. Fixed in 11.1.1. How to fix ↓
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Background
jsrsasign is a popular JavaScript library used for cryptographic operations, including digital signatures and key management. It provides developers with tools to implement secure communications and data integrity in web applications. However, certain versions of jsrsasign are vulnerable to a critical issue that can compromise the security of DSA private keys.
Vulnerability Detail
The vulnerability arises from an incomplete comparison in the jsrsasign library, specifically within the getRandomBigIntegerZeroToMax and getRandomBigIntegerMinToMax functions in src/crypto-1.1.js. This flaw allows an attacker to exploit incorrect comparison checks that accept out-of-range candidates, leading to biased DSA nonces during signature generation. As a result, an attacker can potentially recover the private key, posing a significant risk to the confidentiality and integrity of the cryptographic operations performed by applications using this library.
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
11.1.1
This is the first release that contains the fix.
npm install jsrsasign@11.1.1Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If immediate updating is not feasible, consider implementing additional checks in your code to validate the nonce generation process. However, this is not a substitute for updating the library and should only be a temporary measure.
Conclusion
The jsrsasign library has a critical vulnerability that allows for DSA private key recovery due to improper nonce generation. It is crucial for developers using this library to update to the latest version to mitigate the risk. Utilizing tools like Vulert can help monitor for such vulnerabilities in real-time.
See every vulnerability recorded for jsrsasign →
FAQ
The vulnerability has a CVSS score of 9.1, indicating it is critical and poses a significant risk to affected systems.
Versions of jsrsasign from 7.0.0 up to, but not including, 11.1.1 are vulnerable.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. By using the Vulert playground, you can check if your application is affected without any signup.
If exploited, this vulnerability can lead to the recovery of private keys, compromising the security of cryptographic operations and potentially allowing unauthorized access to sensitive data.
While the best course of action is to update the library, you can implement additional nonce validation checks as a temporary workaround.
References
Related vulnerabilities
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