CVE-2021-26084: Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection Vulnerability

How to check if you are exposed to CVE-2021-26084

1. Find every Atlassian Confluence Server and Data Center system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
2. Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2021-26084.

US federal agencies had to fix this by 2021-11-17. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Timeline

1. 2021-11-03 · Added to CISA's Known Exploited Vulnerabilities catalog
2. 2021-11-17 · Fix-by date for US federal agencies, passed 1,810 days ago

Weakness type

• CWE-917

More exploited Atlassian vulnerabilities

CISA lists 14 exploited Atlassian vulnerabilities. The closest matches:

• CVE-2019-3398Atlassian Confluence Server and Data Center Path Traversal VulnerabilityAdded 2021-11-03
• CVE-2026-21589Atlassian Multiple Products Files or Directories Accessible to External Parties VulnerabilityAdded 2026-10-15
• CVE-2021-26086Atlassian Jira Server and Data Center Path Traversal VulnerabilityAdded 2024-11-12
• CVE-2023-22527Atlassian Confluence Data Center and Server Template Injection VulnerabilityAdded 2024-01-24
• CVE-2023-22518Atlassian Confluence Data Center and Server Improper Authorization VulnerabilityAdded 2023-11-07
• CVE-2023-22515Atlassian Confluence Data Center and Server Broken Access Control VulnerabilityAdded 2023-10-05
• CVE-2022-36804Atlassian Bitbucket Server and Data Center Command Injection VulnerabilityAdded 2022-09-30
• CVE-2022-26138Atlassian Questions For Confluence App Hard-coded Credentials VulnerabilityAdded 2022-07-29

Keep going

• All exploited CVEs
• Check another CVE
• What is CISA KEV?
• What is EPSS?

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.