GMS-2016-83: Forgeable Public/Private Tokens

October 31, 2016

“algorithm” isn’t enforced in jwt.decode() and a malicious user could choose what algorithm is sent sent to the server. If the server is expecting RSA but is sent HMAC-SHA with RSA’s public key, the server will think the public key is actually an HMAC private key. This could be used to forge any data an attacker wants.

References

auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/
github.com/hokaccha/node-jwt-simple/pull/14
github.com/hokaccha/node-jwt-simple/pull/16

Code Behaviors & Features

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