Multiple Products Security Advisory - Unrendered unicode bidirectional override characters - CVE-2021-42574

Summary of Vulnerability

This advisory discloses a high severity security vulnerability which was introduced in multiple product versions as enumerated below:

Bamboo Server and Data Center

• All versions before 8.0.4

Bitbucket Server and Data Center

• All versions before 6.10.14

• All versions between 7.0.0 and 7.5.2 (inclusive)

• All 7.6.x LTS versions before 7.6.10

• All versions between 7.7.0 and 7.16.1 (inclusive)

• All 7.17.x LTS versions before 7.17.1

Confluence Server and Data Center

• All versions before 7.4.13

• All versions between 7.5.0 and 7.12.5 (inclusive)

• All 7.13.x LTS versions before 7.13.2

• Version 7.14.0

Crucible

• All versions before 4.8.8

Fisheye

• All versions before 4.8.8

Jira Service Management Server and Data Center

• All versions before 4.13.13

• All versions between 4.14.0 and 4.19.1 (inclusive)

• All 4.20.x LTS versions before 4.20.1

Insight Asset Management (Marketplace app for Jira Service Management)

• All versions before 8.9.4

Jira Software Server and Data Center (including Jira Core)

• All versions before 8.13.13

• All versions between 8.14.0 and 8.19.1 (inclusive)

• All 8.20.x LTS versions before 8.20.1

CVE-2021-42574 - Unicode bidirectional override character trojan source attack

Severity

Atlassian rates the severity level of this vulnerability as high, according to the scale published in our Atlassian severity levels. The scale allows us to rank the severity as critical, high, moderate or low.

This is our assessment and you should evaluate its applicability to your own IT environment.

Description

A vulnerability has been identified affecting multiple Atlassian products where special characters, known as Unicode bidirectional override characters, are not rendered or displayed in the affected applications. These special characters are typically not displayed by the browser or code editors but can affect the meaning of the source code when it is processed by a compiler or an interpreter.

Acknowledgements

The issue was identified and reported by Nicholas Boucher and Ross Anderson of the University of Cambridge. Details are disclosed at CVE-2021-42574.

Fix

We have taken the following steps to address this issue:

1. Released Bamboo Server and Data Center version 8.0.4 that contains a fix for this issue.

2. Released Bitbucket Server and Data Center versions 6.10.14, 7.6.10, and 7.17.1 that contains a fix for this issue.

3. Released Confluence Server and Data Center versions 7.4.13, 7.13.2, and 7.14.1 that contains a fix for this issue.

4. Released Crucible version 4.8.8 that contains a fix for this issue.

5. Released Fisheye version 4.8.8 that contains a fix for this issue.

6. Released Insight Asset Management marketplace app version 8.9.4 that contains a fix for this issue.

7. Released Jira Service Management Server and Data Center versions 4.13.13, and 4.20.1 that contains a fix for this issue.

8. Released Jira Software Server and Data Center versions 8.13.13, and 8.20.1 that contains a fix for this issue.

What you need to do

Atlassian recommends that you upgrade to the latest version. For a full description of the latest versions, see the release notes for your product:

• Bamboo Server and Data Center release notes
• Bitbucket Server and Data Center release notes

• Confluence Server and Data Center release notes

• Crucible release notes

• Fisheye release notes

• Jira Service Management Server and Data Center release notes

• Jira Software Server and Data Center release notes

You can download the latest version of your product from the download center:

• Download Bamboo Server and Data Center

• Download Bitbucket Server and Data Center

• Download Confluence Server and Data Center

• Download Crucible

• Download Fisheye

• Download Insight Asset Management

• Download Jira Service Management Server and Data Center

• Download Jira Software Server and Data Center

Upgrade to the version recommended below or higher.

Mitigation

The fix involved updating a number of common places where code is displayed, such as in a pull request, code snippet, or code block, to highlight bidirectional characters. A tooltip prompts users to take some time to understand what the characters are doing, and how the code will be interpreted when executed.

Here's an example of the message when viewing a Confluence Data Center page with a code block.

Support

If you did not receive an email for this advisory and you wish to receive such emails in the future go to https://my.atlassian.com/email and subscribe to Alerts emails.

If you have questions or concerns regarding this advisory, check our Frequently asked questions for CVE-2021-42574, or raise a support request at https://support.atlassian.com/.

References