CVE-2021-26073: Atlassian Connect Express

High severity, CVSS 7.7. EPSS: 0.9% chance of exploitation in the next 30 days.

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 from 3.0.2 before 6.6.0 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.

Affected products

• Atlassian Connect Express: from 3.0.2, before 6.6.0 (fixed in 6.6.0)

Published 2021-04-16. Last modified 2026-06-17.