wolfSSL's ECCSI signature verifier wc_VerifyEccsiHash decodes the r and s scalars from the signature blob via mp_read_unsigned_bin with no check that they lie in [1, q-1]. A crafted forged signature could verify against any message for any identity, using only publicly-known constants.
Exploitability
AV:AAC:LAT:PPR:NUI:NVulnerable System
VC:HVI:HVA:NSubsequent System
SC:NSI:NSA:N7.6/CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NOther