CVE-2021-26084 Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection Vulnerability
Atlassian Confluence Server and Data Server contain an Object-Graph Navigation Language (OGNL) injection vulnerability that may allow an unauthenticated attacker to execute code.
From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.
Should You Worry?
- CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 3 Nov 2021.
- CISA lists it as known to be used in ransomware campaigns.
- Rated Critical severity (CVSS 9.8, scored by CISA).
- This product type is often exposed to the internet, which is where attackers scan for it first.
- It has been in the catalogue for 1,829 days. Systems still unpatched now have almost certainly been scanned for it.
What It Is
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.
Affected Versions
| Product | Versions |
|---|---|
| Atlassian Confluence Server | unspecified to before 6.13.23 6.14.0 to before unspecified unspecified to before 7.4.11 7.5.0 to before unspecified unspecified to before 7.11.6 7.12.0 to before unspecified |
| Atlassian Confluence Data Center | unspecified to before 6.13.23 6.14.0 to before unspecified unspecified to before 7.4.11 7.5.0 to before unspecified unspecified to before 7.11.6 7.12.0 to before unspecified |
From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.
What To Do Now
- 1
Find it
Search your asset inventory and external attack surface for Atlassian Confluence Server and Data Center. Include cloud images, appliances and anything a supplier runs for you.
Attack Surface Management - 2
- 3
Hunt for compromise
If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.
Incident Response - 4
Prove it is fixed
Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.
Penetration Testing
Vendor Advisories
The Compliance Clock
General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.
Not Sure If You Are Exposed?
Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2021-26084 and every other exploited flaw on the list.