Summary
Improper validation of the JWT NumericDate claims exp, nbf, and iat in hono/utils/jwt allows tokens with non-spec-compliant claim values to silently bypass time-based checks. This issue is not exploitable by an anonymous attacker; it only manifests when a malformed claim value reaches verify() — typically when the application itself issues such tokens, or when the signing key is otherwise under attacker control.
Details
The validation routine combined option, presence, and threshold checks in a single short-circuiting expression, so several classes of malformed values were silently skipped instead of rejected:
- A falsy numeric value short-circuited the presence check.
- A non-finite numeric value compared as never-after-now and never-expired.
- A non-numeric type produced NaN comparisons that evaluated false.
This deviates from RFC 7519 §4.1.4, which defines NumericDate as a finite JSON numeric value.
Impact
An actor able to issue tokens accepted by the application may craft tokens whose exp, nbf, or iat claims silently bypass time-based enforcement. This may lead to:
- Tokens treated as never expiring even with
exp configured on the verifier.
- Tokens with a future
nbf accepted as currently valid.
- Tokens with a future
iat accepted as legitimately issued.
Deployments using a well-formed token issuer and protecting the signing key are not affected.
References
AdmirBajric Reporter
Summary
Improper validation of the JWT NumericDate claims
exp,nbf, andiatinhono/utils/jwtallows tokens with non-spec-compliant claim values to silently bypass time-based checks. This issue is not exploitable by an anonymous attacker; it only manifests when a malformed claim value reachesverify()— typically when the application itself issues such tokens, or when the signing key is otherwise under attacker control.Details
The validation routine combined option, presence, and threshold checks in a single short-circuiting expression, so several classes of malformed values were silently skipped instead of rejected:
This deviates from RFC 7519 §4.1.4, which defines NumericDate as a finite JSON numeric value.
Impact
An actor able to issue tokens accepted by the application may craft tokens whose
exp,nbf, oriatclaims silently bypass time-based enforcement. This may lead to:expconfigured on the verifier.nbfaccepted as currently valid.iataccepted as legitimately issued.Deployments using a well-formed token issuer and protecting the signing key are not affected.
References