GHSA-5jjv-x4fq-qjwp Possible timing attack in derivation_endpoint

• RubyGems shrine: < 3.3.0 → fixed in 3.3.0

Impact When using the `derivation_endpoint` plugin, it's possible for the attacker to use a timing attack to guess the signature of the derivation URL. Patches The problem has been fixed by comparing sent and calculated signature in constant time, using `Rack::Utils.secure_compare`. Users using the `derivation_endpoint` plugin are urged to upgrade to Shrine 3.3.0 or greater. Workarounds Users of older Shrine versions can apply the following monkey-patch after loading the `derivation_endpoint` plugin: ```rb class Shrine class UrlSigner def verify_signature(string, signature) if signature.nil? fail InvalidSignature, "missing \"signature\" param" elsif !Rack::Utils.secure_compare(signature, generate_signature(string)) fail InvalidSignature, "provided signature does not match the calculated signature" end end end end ``` References You can read more about timing attacks here.