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Fix path traversal via double percent-encoded slash bypassing directory containment #154

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Fix path traversal via double percent-encoded slash bypassing directory containment #154

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8 changes: 8 additions & 0 deletions server.js
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Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,14 @@ export default class EleventyDevServer {

computedPath = decodeURIComponent(computedPath);

// Reject a literal `..` path segment that only appears after percent-decoding.
// This closes a bypass where a `%2f`-encoded separator survives the URL layer's
// own dot-segment normalization (which only recognizes literal `/`), then decodes
// into a real `../` here, escaping `this.dir` via a same-prefix sibling directory.
if(computedPath.split(path.sep).includes("..")) {
throw new Error("Invalid path");
}

if(!filename) { // is a direct URL request (not an implicit .html or index.html add)
let alias = this.matchPassthroughAlias(filepath);

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