fix(core): prevent infinite recursion in symlink resolution (#21750)

packages/core/src/utils/paths.test.ts

@@ -484,6 +484,10 @@ describe('shortenPath', () => {
 });
 
 describe('resolveToRealPath', () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
   it.each([
     {
       description:
@@ -542,6 +546,28 @@ describe('resolveToRealPath', () => {
 
     expect(resolveToRealPath(childPath)).toBe(expectedPath);
   });
+
+  it('should prevent infinite recursion on malicious symlink structures', () => {
+    const maliciousPath = path.resolve('malicious', 'symlink');
+
+    vi.spyOn(fs, 'realpathSync').mockImplementation(() => {
+      const err = new Error('ENOENT') as NodeJS.ErrnoException;
+      err.code = 'ENOENT';
+      throw err;
+    });
+
+    vi.spyOn(fs, 'lstatSync').mockImplementation(
+      () => ({ isSymbolicLink: () => true }) as fs.Stats,
+    );
+
+    vi.spyOn(fs, 'readlinkSync').mockImplementation(() =>
+      ['..', 'malicious', 'symlink'].join(path.sep),
+    );
+
+    expect(() => resolveToRealPath(maliciousPath)).toThrow(
+      /Infinite recursion detected/,
+    );
+  });
 });
 
 describe('normalizePath', () => {

packages/core/src/utils/paths.ts

@@ -375,7 +375,12 @@ export function resolveToRealPath(pathStr: string): string {
   return robustRealpath(path.resolve(resolvedPath));
 }
 
-function robustRealpath(p: string): string {
+function robustRealpath(p: string, visited = new Set<string>()): string {
+  const key = process.platform === 'win32' ? p.toLowerCase() : p;
+  if (visited.has(key)) {
+    throw new Error(`Infinite recursion detected in robustRealpath: ${p}`);
+  }
+  visited.add(key);
   try {
     return fs.realpathSync(p);
   } catch (e: unknown) {
@@ -385,14 +390,25 @@ function robustRealpath(p: string): string {
         if (stat.isSymbolicLink()) {
           const target = fs.readlinkSync(p);
           const resolvedTarget = path.resolve(path.dirname(p), target);
-          return robustRealpath(resolvedTarget);
+          return robustRealpath(resolvedTarget, visited);
+        }
+      } catch (lstatError: unknown) {
+        // Not a symlink, or lstat failed. Re-throw if it's not an expected
+        // ENOENT (e.g., a permissions error), otherwise resolve parent.
+        if (
+          !(
+            lstatError &&
+            typeof lstatError === 'object' &&
+            'code' in lstatError &&
+            lstatError.code === 'ENOENT'
+          )
+        ) {
+          throw lstatError;
         }
-      } catch {
-        // Not a symlink, or lstat failed. Just resolve parent.
       }
       const parent = path.dirname(p);
       if (parent === p) return p;
-      return path.join(robustRealpath(parent), path.basename(p));
+      return path.join(robustRealpath(parent, visited), path.basename(p));
     }
     throw e;
   }