CVE intelligenceCISA KEVRansomware use

CVE-2021-26084

Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection Vulnerability

Published Aug 30, 2021Sources checked Sep 12, 2026

9.8CRITICALCVSS out of 10

What this means

Actively exploited

CISA lists CVE-2021-26084 in its Known Exploited Vulnerabilities catalog, which means exploitation has been observed. The entry applies to Atlassian Confluence Server and Data Center.

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CISA KEVListedObserved exploitation

EPSS100.0%Estimated 30-day exploitation probability

Ransomware useReported by CISACISA KEV ransomware field

Threat actors2Source-linked actor relationships

Overview

What is CVE-2021-26084?

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.