Broken Authentication in Atlassian Connect Express

Exploitation

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

CVSS

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

EPSS

• CVE-2021-26073: 0.92% estimated exploitation activity in the next 30 days; percentile 60.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Broken Authentication in Atlassian Connect Express (ACE) from version 3.0.2 before version 6.6.0: Atlassian Connect Express is a Node.js package for building Atlassian Connect apps. Authentication between Atlassian products and the Atlassian Connect Express app occurs with a server-to-server JWT or a context JWT. Atlassian Connect Express versions between 3.0.2 - 6.5.0 erroneously accept context JWTs in lifecycle endpoints (such as installation) where only server-to-server JWTs should be accepted, permitting an attacker to send authenticated re-installation events to an app.

Published by the source

24 May 2022, 22:28 UTC

Last modified by the source

12 Feb 2025, 22:27 UTC

Source last checked

26 Oct 2026, 12:36 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4v96-m8xv-x83v

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4v96-m8xv-x83v

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# Patch Next advisory brief: CVE-2021-26073

Advisory: Broken Authentication in Atlassian Connect Express
IDs: CVE-2021-26073, GHSA-4v96-m8xv-x83v
Record: https://patchnext.com/advisories/cve-2021-26073 (revision 2, source checked 26 Oct 2026, 12:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: atlassian-connect-express 6.6.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm atlassian-connect-express: affected >= 3.0.2, < 6.6.0; fixed in 6.6.0

## Suggested inspection (read-only)
- `npm ls atlassian-connect-express --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## 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 atlassian-connect-express.
- 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://osv.dev/vulnerability/GHSA-4v96-m8xv-x83v (OSV record GHSA-4v96-m8xv-x83v lists affected ranges: npm atlassian-connect-express >=3.0.2 <6.6.0 (fixed))
- Verified: https://github.com/advisories/GHSA-4v96-m8xv-x83v (GitHub-reviewed advisory GHSA-4v96-m8xv-x83v lists affected ranges: npm atlassian-connect-express >=3.0.2 <6.6.0)

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