critical Known exploitedREV. 01
CVE-2021-26084Confluence Server & Data Center — OGNL Injection (2021)
Older Confluence Server and Data Center releases evaluate attacker-supplied text as program code, letting an unauthenticated visitor execute commands on the wiki server. Ransomware crews are known to use it.
Read the risk
THE VITAL STATS- CVSS score
- 9.8/ 10 CVSS v3.1
- EPSS probability
- 100% Likelihood of exploitation
- Attack complexity
- Low Conditions needed to exploit
- Known exploited
- Yes — CISA KEV
- CVE published
- 2021-08-30
- Added to KEV
- 2021-11-03
- Exploit published
- Yes
- Confidence
- high
- Kill chain
- initial access
- MITRE ATT&CK
- T1190
- Severity
- critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attacker needsNetwork access to a self-hosted Confluence instance in an affected version range. No credentials needed.
Fixed inConfluence 6.13.23, Confluence 7.4.11, Confluence 7.11.6, Confluence 7.12.5
Behind the card
4 REFERENCES- 01CVE recordNVD recordnvd.nist.gov
- 02Vendor advisoryAtlassian issue CONFSERVER-67940jira.atlassian.com
- 03ExploitPublic expression-injection exploitpacketstormsecurity.com
- 04CISACISA Known Exploited Vulnerabilities entrycisa.gov
Field-level provenanceTRACE THE SOURCES +
Which source supports each field, when it was retrieved, and who extracted it.
| Fields | Source | Retrieved | Extractor | Confidence |
|---|---|---|---|---|
| title, summary, cvss, severity, exploitation.attack_complexity, exploitation.prerequisites, exploitation.exploit_available, remediation, references | nvd.nist.gov | 2026-08-07 | claude-code | high |
| exploitation.known_exploited, summary, recommended_action | cisa.gov | 2026-08-07 | claude-code | high |
| epss | api.first.org | 2026-08-07 | claude-code | high |
Printing history
THE RECORD- r1Initial base card
First printing. This card has not been reprinted since publication.