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.

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！

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2022-26652 has a CVSS score of 6.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.7.4, 0.24.3); upgrading removes the vulnerable code path.

Kodem intelligence

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.

1. What is CVE-2022-26652? CVE-2022-26652 is a high-severity path traversal vulnerability in github.com/nats-io/nats-server/v2 (go), affecting versions >= 2.2.0, < 2.7.4. It is fixed in 2.7.4, 0.24.3. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2022-26652? CVE-2022-26652 has a CVSS score of 6.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2022-26652?
   • github.com/nats-io/nats-server/v2 (go) (versions >= 2.2.0, < 2.7.4)
   • github.com/nats-io/nats-streaming-server (go) (versions >= 0.15.0, < 0.24.3)
4. Is there a fix for CVE-2022-26652? Yes. CVE-2022-26652 is fixed in 2.7.4, 0.24.3. Upgrade to this version or later.
5. Is CVE-2022-26652 exploitable, and should I be worried? Whether CVE-2022-26652 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2022-26652 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2022-26652?
   • Upgrade github.com/nats-io/nats-server/v2 to 2.7.4 or later
   • Upgrade github.com/nats-io/nats-streaming-server to 0.24.3 or later