The following errata report has been submitted for RFC7519, "JSON Web Token (JWT)".
-------------------------------------- You may review the report below and at: https://www.rfc-editor.org/errata/eid5906 -------------------------------------- Type: Technical Reported by: Erdem Memisyazici <[email protected]> Section: 7.2 Original Text ------------- Finally, note that it is an application decision which algorithms may be used in a given context. Even if a JWT can be successfully validated, unless the algorithms used in the JWT are acceptable to the application, it SHOULD reject the JWT. Corrected Text -------------- Finally, note that it is an application decision which algorithms may be used in a given context. Even if a JWT can be successfully validated, unless the algorithms used in the JWT are acceptable to the application, it MUST reject the JWT. Notes ----- A vulnerability exists in certain implementations in the wild where applications simply look for valid JWT tokens which includes the "none" algorithm (https://medium.com/swlh/hacking-json-web-tokens-jwts-9122efe91e4a). A fairly popular library is auth0's java-jwt and at verification (https://github.com/auth0/java-jwt/blob/master/lib/src/main/java/com/auth0/jwt/JWTVerifier.java) quite reasonably you cannot initialize the class without an algorithm. Given all capital SHOULD may be interpreted as a recommendation and as this RFC dictates the algorithm "none" MUST be implemented as a default algorithm under Section 8, one could argue JWTVerifier in the example doesn't have to verifyAlgorithm leading to the vulnerability pointed out in the first article while still complying by the specification. There is no good reason why an algorithm unacceptable to the application must not be rejected as it does more harm than good and all popular library implementations interpret it as such. Instructions: ------------- This erratum is currently posted as "Reported". If necessary, please use "Reply All" to discuss whether it should be verified or rejected. When a decision is reached, the verifying party can log in to change the status and edit the report, if necessary. -------------------------------------- RFC7519 (draft-ietf-oauth-json-web-token-32) -------------------------------------- Title : JSON Web Token (JWT) Publication Date : May 2015 Author(s) : M. Jones, J. Bradley, N. Sakimura Category : PROPOSED STANDARD Source : Web Authorization Protocol Area : Security Stream : IETF Verifying Party : IESG _______________________________________________ OAuth mailing list [email protected] https://www.ietf.org/mailman/listinfo/oauth
