# CVE-2026-4603

## Summary

- **CVE ID:** CVE-2026-4603
- **Severity:** MEDIUM
- **CVSS Score:** 5.9 (CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P)
- **CWE:** CWE-369
- **Published:** Mar 23, 2026
- **Last Modified:** Mar 23, 2026

## Description

Versions of the package jsrsasign before 11.1.1 are vulnerable to Division by zero due to the RSASetPublic/KEYUTIL parsing path in ext/rsa.js and the BigInteger.modPowInt reduction logic in ext/jsbn.js. An attacker can force RSA public-key operations (e.g., verify and encryption) to collapse to deterministic zero outputs and hide “invalid key” errors by supplying a JWK whose modulus decodes to zero.

## Affected Products

- n/a — jsrsasign (0)

## References

- [CNA](https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371176)
- [CNA](https://gist.github.com/Kr0emer/5366b7364c4fbf7e754bc377f321e9f3)
- [CNA](https://github.com/kjur/jsrsasign/commit/dc41d49fac4297e7a737a3ef8ebd0aa9c49ef93f)
- [CNA](https://github.com/kjur/jsrsasign/pull/649)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.10%
- **EPSS Percentile:** 0.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._