CVE-2022-26652

(This document is canonically: <https://advisories.nats.io/CVE/CVE-2022-26652.txt>) ## Background NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing. JetStream is the optional RAFT-based resilient persistent feature of NATS. ## Problem Description The JetStream streams can be backed up and restored via NATS. The backup format is a tar archive file. Inadequate checks on the filenames within the archive file permit a so-called "Zip Slip" attack in the stream restore. NATS nats-server through 2022-03-09 (fixed in release 2.7.4) did not correctly sanitize elements of the archive file, thus a user of NATS could cause the NATS server to write arbitrary content to an attacker-controlled filename. ## Affected versions NATS Server: * 2.2.0 up to and including 2.7.3. + Introduced with JetStream Restore functionality * Fixed with nats-io/nats-server: 2.7.4 * Docker image: nats <https://hub.docker.com/_/nats> * NB users of OS package files from our releases: a change in goreleaser defaults, discovered late in the release process, moved the install directory from /usr/local/bin to /usr/bin; we are evaluating the correct solution for subsequent releases, but not recutting this release. NATS Streaming Server * 0.15.0 up to and including 0.24.2 * Fixed with nats-io/nats-streaming-server: 0.24.3 * Embeds a nats-server, but this server is the old approach which JetStream replaces, so unlikely (but not impossible) to be configured with JS support ## Workarounds * Disable JetStream for untrusted users. * If only one NATS account uses JetStream, such that cross-user attacks are not an issue, and any user in that account with access to the JetStream API is fully trusted anyway, then appropriate sandboxing techniques will prevent exploit. + Eg, with systemd, the supplied util/nats-server-hardened.service example configuration demonstrates that NATS runs fine as an unprivileged user under ProtectSystem=strict and PrivateTmp=true restrictions; by only opening a ReadWritePaths hole for the JetStream storage area, the impact of this vulnerability is limited. ## Solution Upgrade the NATS server to at least 2.7.4. We fully support the util/nats-server-hardened.service configuration for running a NATS server and encourage this approach. ## Credits This issue was reported (on 2022-03-07) to the NATS Maintainers by Yiming Xiang, TIANJI LAB of NSFOCUS. Thank you / 谢谢你！

NATS nats-server before 2.7.4 allows Directory Traversal (with write access) via an element in a ZIP archive for JetStream streams. nats-streaming-server before 0.24.3 is also affected.

Arbitrary file write in nats-server in github.com/nats-io/nats-server