CVE-2021-26084
CRITICALCISA KEVEPSS 100th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
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.
Apply updates per vendor instructions.
Remediation due: 2021-11-17
Associated with ransomware campaigns
References
Related Vulnerabilities
Other CWE-917 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-26134 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2021-44228 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2021-45046 | Critical | 9.0 | 100% | KEV + Ransom | Fix |
| CVE-2022-22963 | Critical | 9.8 | 100% | KEV | - |
| CVE-2020-10199 | High | 8.8 | 99% | KEV | Fix |
| CVE-2022-22947 | Critical | 10.0 | 98% | KEV | Fix |
Common questions
How do I fix CVE-2021-26084?
Published advisories record a fix for 2 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-26084 being actively exploited?
Yes. CVE-2021-26084 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. CISA has also linked it to known ransomware campaigns. US federal agencies were required to remediate it by 2021-11-17. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2021-26084?
CVE-2021-26084 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-26084 affect?
Published advisories record a fix for confluence data center (NVD), confluence server (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-24.