https://github.com/vercel/next.js/compare/v15.0.4...v15.0.5
It looks like the fix is checking hasOwnProperty, so it's almost certainly an issue with prototype chain pollution.
return "*" === metadata[2]
? moduleExports
: "" === metadata[2]
? moduleExports.__esModule
? moduleExports.default
: moduleExports
: moduleExports[metadata[2]];