Sparkle's AppInstaller post-stage-1 XPC listener accepts unvalidated connections, allowing spoofed appcast item data injection
Sparkle is a software update framework for macOS. In versions up to and including 2.9.1, `Autoupdate/AppInstaller.m`'s `shouldAcceptNewConnection:` only enforces `SUCodeSigningVerifier validateConnection:` before stage 1 completes. After `_performedStage1Inst…