EUVD-2026-21291
GHSA-47qf-hp3h-rwmm
CVSS Vector
CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
3Description
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.
Analysis
Signature verification bypass in wolfSSL's ECCSI implementation allows adjacent network attackers to forge cryptographic signatures for any message and identity without authentication. The wc_VerifyEccsiHash function fails to validate that signature scalars r and s fall within the required mathematical range [1, q-1], enabling attackers with knowledge of public constants to craft universally-valid forged signatures. …
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Remediation
Within 24 hours: Identify all systems using wolfSSL ECCSI functionality, particularly those handling JWT authentication or identity-based cryptography, and document network boundaries with adjacent systems. Within 7 days: Implement network segmentation to restrict ECCSI-signed communication to trusted adjacent networks only; engage wolfSSL support for security guidance and monitor for patch availability. …
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External POC / Exploit Code
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