March 28, 2022 · Applied Cybernetics Group
CVE-2021-26085 Atlassian Confluence Server
known ransomware use
Atlassian Confluence Server Pre-Authorization Arbitrary File Read Vulnerability
- Added to KEV
2022-03-28- Federal due date
2022-04-18- Vendor
- Atlassian
- Product
- Confluence Server
- EPSS
- 100.0th percentile (score 0.999, as of
2026-11-06) - NVD CVSS v3.1
- —
- Ransomware use
- Known
- ATT&CK
- T1005 , T1190 · signal rollup
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2021-26085
CISA short description
Affected versions of Atlassian Confluence Server allow remote attackers to view restricted resources via a pre-authorization arbitrary file read vulnerability in the /s/ endpoint.
Required action
Apply updates per vendor instructions.