RSA-PSS signature validation vulnerability by prepending zeros in jsrsasign

Impact

Jsrsasign can verify RSA-PSS signature which value can expressed as BigInteger. When there is a valid RSA-PSS signature value, this vulnerability is also accept value with prepending zeros as a valid signature.

• If you are not use RSA-PSS signature validation, this vulnerability is not affected.
• Risk to accept a forged or crafted message to be signed is low.
• Risk to raise memory corruption is low since jsrsasign uses BigInteger class.

Patches

Users using RSA-PSS signature validation should upgrade to 8.0.17.

Workarounds

Reject RSA-PSS signatures with unnecessary prepending zeros.

References

https://github.com/kjur/jsrsasign/security/advisories/GHSA-q3gh-5r98-j4h3
https://github.com/kjur/jsrsasign/issues/438
https://nvd.nist.gov/vuln/detail/CVE-2020-14968
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14968
https://vuldb.com/?id.157125
https://kjur.github.io/jsrsasign/api/symbols/RSAKey.html#.verifyWithMessageHashPSS