CVE-2021-26077

Name: CVE-2021-26077
Creator: NVD / NIST
Published: 2021-05-10T00:15:07.543+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 0.95%

Last modified Jun 17, 2026

CVE-2021-26077 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. Broken Authentication in Atlassian Connect Spring Boot (ACSB) in version 1.1.0 before 2.1.3 and from version 2.1.4 before 2.1.5: Atlassian Connect Spring Boot is a Java Spring Boot package for building Atlassian Connect apps. Authentication between Atlassian products and the Atlassian Connect Spring Boot app occurs with a server-to-server JWT or a context JWT. EPSS estimates a 0.95% chance of exploitation in the next 30 days.

Description

Broken Authentication in Atlassian Connect Spring Boot (ACSB) in version 1.1.0 before 2.1.3 and from version 2.1.4 before 2.1.5: Atlassian Connect Spring Boot is a Java Spring Boot package for building Atlassian Connect apps. Authentication between Atlassian products and the Atlassian Connect Spring Boot app occurs with a server-to-server JWT or a context JWT. Atlassian Connect Spring Boot versions 1.1.0 before 2.1.3 and versions 2.1.4 before 2.1.5 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.

Metrics

CVSS 3.1

8.8/10

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

EPSS Probability

0.95%

56.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Atlassian	Connect Spring Boot	>= 1.1.0, < 2.1.3
Atlassian	Connect Spring Boot	>= 2.1.4, < 2.1.5

References

https://community.developer.atlassian.com/t/action-required-atlassian-connect-vulnerability-allows-bypass-of-app-qsh-verification-via-context-jwts/47072Exploit, Issue Tracking, Vendor Advisory
https://confluence.atlassian.com/pages/viewpage.action?pageId=1063555147Vendor Advisory
https://community.developer.atlassian.com/t/action-required-atlassian-connect-vulnerability-allows-bypass-of-app-qsh-verification-via-context-jwts/47072Exploit, Issue Tracking, Vendor Advisory
https://confluence.atlassian.com/pages/viewpage.action?pageId=1063555147Vendor Advisory

Timeline

Published: May 10, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-26077?

How severe is CVE-2021-26077?

CVE-2021-26077 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.95% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26077?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-26077?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST