CVE-2020-14968: 
JavaScript vulnerability analysis and mitigation

An issue was discovered in the jsrsasign package before 8.0.17 for Node.js. Its RSASSA-PSS (RSA-PSS) implementation does not detect signature modification when prepending zeros to the signature, allowing potential signature forgery (NVD, GitHub Release).

The vulnerability exists in the RSA-PSS signature validation implementation where the code fails to properly validate signatures that have been modified by prepending zero bytes. This security flaw affects the verifyWithMessageHashPSS function in the signature verification process. The issue was fixed in version 8.0.17 by implementing proper validation checks for prepended zeros in signatures (GitHub Issue).

The vulnerability could allow an attacker to forge signatures by modifying existing valid signatures through prepending zero bytes. This could lead to unauthorized access or compromise of systems relying on RSA-PSS signature verification for authentication or integrity checks (NetApp Advisory).

The vulnerability can be exploited by an attacker who can intercept and modify RSA-PSS signatures by prepending zero bytes to valid signatures. The modified signatures would still be accepted as valid by affected versions of the library (GitHub Issue).

Users should upgrade to jsrsasign version 8.0.17 or later which includes the fix for this vulnerability. The fix implements proper validation checks to detect and reject signatures that have been modified by prepending zeros (GitHub Release).