Import loops in account imports, nats-server DoS

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

(This advisory is canonically <https://advisories.nats.io/CVE/CVE-2020-28466.txt) Problem Description An export/import cycle between accounts could crash the nats-server, after consuming CPU and memory. This issue was fixed publicly in <https://github.com/nats-io/nats-server/pull/1731 in November 2020. The need to call this out as a security issue was highlighted by snyk.io and we are grateful for their assistance in doing so. Organizations which run a NATS service providing access to accounts run by untrusted third parties are affected. See below for an important caveat if running such a service. Affected versions NATS Server Version 2 prior to 2.2.0 + 2.0.0 through and including 2.1.9 are vulnerable. fixed with nats-io/nats-server PR 1731, commit 2e3c226729 Impact The nats-server could be killed, after consuming resources. Workaround The import cycle requires at least two accounts to work; if you have open account sign-up, then restricting new account sign-up might hinder an…

Published by the source

21 May 2021, 16:22 UTC

Last modified by the source

9 Jan 2023, 05:04 UTC

Source last checked

26 Oct 2026, 14:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gwj5-3vfq-q992

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# Patch Next advisory brief: GHSA-gwj5-3vfq-q992

Advisory: Import loops in account imports, nats-server DoS
IDs: GHSA-gwj5-3vfq-q992
Record: https://patchnext.com/advisories/ghsa-gwj5-3vfq-q992 (revision 1, source checked 26 Oct 2026, 14:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/nats-io/nats-server/v2 2.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/nats-io/nats-server/v2: affected < 2.2.0; fixed in 2.2.0

## Suggested inspection (read-only)
- Go github.com/nats-io/nats-server/v2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/nats-io/nats-server/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-gwj5-3vfq-q992 (GitHub-reviewed advisory GHSA-gwj5-3vfq-q992 lists affected ranges: Go github.com/nats-io/nats-server/v2 >=0 <2.2.0)

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