What’s Vulnerable › Vulnerabilities

CVE-2021-26073

• Severity: high (CVSS 7.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-04-16 · updated 2026-06-17
• Weakness: CWE-287

Description

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 (ACE): from 3.0.2 before 6.6.0 — fixed in 6.6.0

How to fix

Upgrade to a fixed version: Atlassian Connect Express (ACE) 6.6.0. Check the vendor advisory for mitigations.

References

• https://community.developer.atlassian.com/t/action-required-atlassian-connect-vulnerability-a%5B%E2%80%A6%5Dypass-of-app-qsh-verification-via-context-jwts/47072
• https://confluence.atlassian.com/pages/viewpage.action?pageId=1051986099
• https://security.netapp.com/advisory/ntap-20210604-0004/
• https://community.developer.atlassian.com/t/action-required-atlassian-connect-vulnerability-a%5B%E2%80%A6%5Dypass-of-app-qsh-verification-via-context-jwts/47072
• https://confluence.atlassian.com/pages/viewpage.action?pageId=1051986099
• https://security.netapp.com/advisory/ntap-20210604-0004/

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