Bug 2571829 (CVE-2026-123829)

Summary: CVE-2026-123829 nodejs: Node.js: Information disclosure via improper permission checks in recursive file watching
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Node.js. When recursive file watching is used on macOS and Windows systems, the Node.js Permission Model checks read permissions only on the root directory being monitored rather than validating each nested path. A local process running with restricted permissions can exploit this behavior to observe file system events in unauthorized subdirectories. This flaw leads to information disclosure by exposing restricted file and directory names as well as event timing metadata, although it does not expose actual file contents.
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Description OSIDB Bzimport 2026-11-11 18:22:16 UTC 
A Permission Model bypass in Node.js recursive file watching discloses the names of files and directories the process is not permitted to read. On macOS and Windows, fs.watch() and fs.promises.watch() in recursive mode are backed by the native libuv watcher: FSEventWrap::Start checks kFileSystemRead only once, on the watched root, and FSEventWrap::OnEvent then forwards every filename libuv reports (relative paths at any depth) to the JavaScript callback without checking that each path is covered by the read grant. Code running under --permission with an exact read grant on a directory can therefore learn names such as sub/secret.txt even though readdir on that subdirectory is denied. The flaw exposes names and timing metadata, not file contents, and requires macOS or Windows plus files created under the watched directory by another actor. This vulnerability affects Node.js 26.x, 24.x, and 22.x.