CVE-2021-26084 vulnerability in Atlassian Products
Published on August 30, 2021

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated attacker to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0 before 7.12.5.

Vendor Advisory NVD

Known Exploited Vulnerability

This Atlassian Confluence Server < 6.13.23, 6.14.0 - 7.12.5 Arbitrary Code Execution vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Atlassian Confluence Server The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0 before 7.12.5 contains an OGNL injection vulnerability which allows an attacker to execute arbitrary code.

The following remediation steps are recommended / required by November 17, 2021: Apply updates per vendor instructions.

Vulnerability Analysis

CVE-2021-26084 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. It has the highest possible exploitability rating (3.9). The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.

What is an Injection Vulnerability?

The software constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Software has certain assumptions about what constitutes data and control respectively. It is the lack of verification of these assumptions for user-controlled input that leads to injection problems. Injection problems encompass a wide variety of issues -- all mitigated in very different ways and usually attempted in order to alter the control flow of the process. For this reason, the most effective way to discuss these weaknesses is to note the distinct features which classify them as injection weaknesses. The most important issue to note is that all injection problems share one thing in common -- i.e., they allow for the injection of control plane data into the user-controlled data plane. This means that the execution of the process may be altered by sending code in through legitimate data channels, using no other mechanism. While buffer overflows, and many other flaws, involve the use of some further issue to gain execution, injection problems need only for the data to be parsed. The most classic instantiations of this category of weakness are SQL injection and format string vulnerabilities.

CVE-2021-26084 has been classified to as an Injection vulnerability or weakness.

Products Associated with CVE-2021-26084

You can be notified by stack.watch whenever vulnerabilities like CVE-2021-26084 are published in these products:

Atlassian Confluence

Atlassian Data Center

Atlassian Confluence Server

Atlassian Jira Data Center

Atlassian Confluence Data Center

What versions are vulnerable to CVE-2021-26084?