title: Signature forgery in Biscuit
description: Biscuit is an authentication and authorization token for microservices architectures. The Biscuit specification version 1 contains a vulnerable algorithm that allows malicious actors to forge valid Γ-signatures. Such an attack would allow an attacker to create a token with any access level. The version 2 of the specification mandates a different algorithm than gamma signatures and as such is not affected by this vulnerability. The Biscuit implementations in Rust, Haskell, Go, Java and Javascript all have published versions following the v2 specification. There are no known workarounds for this issue.
problem types: CWE-347: Improper Verification of Cryptographic Signature
affected:
{
product: biscuit
vendor: biscuit-auth
versions:
status: affected, version: biscuit-auth >= 1.0.0, < 2.0.0
status: affected, version: biscuit-haskell = 0.1.1.0
status: affected, version: com.clever-cloud.biscuit-java < 2.0.0
status: affected, version: github.com/biscuit-auth/biscuit-go < 2.0
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 9.8
baseSeverity: CRITICAL
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
version: 3.1
]