wolfSSL ECCSI Signature Forgery Vulnerability in Signature Verification

A vulnerability exists in wolfSSL's ECCSI signature verifier function `wc_VerifyEccsiHash`. The issue arises because the function decodes the `r` and `s` scalars from the signature blob using `mp_read_unsigned_bin` without verifying that these values fall within the range of `[1, q-1]`. This lack of validation allows a crafted, forged signature to be accepted as valid for any message and identity, by exploiting publicly known constants.

Impact

Exploitation of this vulnerability allows for the forgery of signatures, enabling a malicious actor to create a false signature that is accepted as legitimate by the signature verification process.

Remediation

Users are advised to update to the latest version of wolfSSL where this vulnerability has been addressed.