@LOGTO/TUNNEL · CVE-2026-63188 · Package
FIX → 0.3.9
The @logto/tunnel npm package serves custom sign-in UI files from a local folder but does not stop '../' segments in request URLs. A network peer can request a path like /../secret.txt and read any file the logto-tunnel process can read.
first public Jul 2, 2026 · 2 sources
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Teams running logto-tunnel with --experience-path to serve custom sign-in UI assets, where the tunnel port is reachable beyond the developer's own machine. Anyone not using the tunnel command or the experience-path option can skip it.
Not affected if no-experience-path, tunnel-not-reachable, version-0.3.9-or-later
Who cares cwe-22, logto, node, npm, self-hosted
npm ls @logto/tunnel; versions 0.3.8 and below are affected.--experience-path and whether its port is reachable from other hosts.Upgrade to 0.3.9
@logto/tunnel 0.3.9@logto/tunnel serves custom sign-in experience files from the --experience-path directory. When the tunnel service is reachable, a requester can use ../ path segments in a static asset request to read files outside that directory that the CLI process can read.
The tunnel command accepts --experience-path as the local folder path for custom sign-in experience assets. packages/tunnel/src/commands/tunnel/index.ts enables createStaticFileProxy(path) when that option is set and sends non-Logto, non---experience-uri requests to that static proxy. The server is started with server.listen(port).
packages/tunnel/src/commands/tunnel/utils.ts builds the filesystem path as path.join(staticPath, fallBackToIndex ? index : request.url). For file asset paths, request.url is used directly. A request URL such as resolves outside and is then opened with . There is no URL normalization and no containment check that the resolved path remains under the configured static directory before the file is read and returned.
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/../secret.txtstaticPathfs.open(requestPath, 'r')The proof boundary is the packaged CLI end-to-end run. The filesystem read primitive was validated with equivalent Node HTTP handling for the affected code path, including that Node preserves /../secret.txt in request.url and that bare server.listen(port) binds to all interfaces on this platform.
/tmp/logto-ui/static with /tmp/logto-ui/static/index.html./tmp/logto-ui/secret.txt.logto-tunnel --endpoint https://<tenant-id>.logto.app --port 9000 --experience-path /tmp/logto-ui/static.http://<host>:9000/../secret.txt./tmp/logto-ui/secret.txt.The observed result is arbitrary file read outside the configured custom UI static directory. If the tunnel port is reachable from another host, an unauthenticated network peer can read local files readable by the logto-tunnel process, including development secrets or credentials stored near the custom UI project.
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