CVE-2026-21589
Atlassian Multiple Products Files or Directories Accessible to External Parties Vulnerability
Multiple Atlassian products (Bitbucket Data Center ,Confluence Data Center, Jira Service Management Data Center, Jira Software Data Center, Bamboo Data Center, Crowd Data Center, Crucible and Fisheye) contain a files or directories accessible to external parties vulnerability which could allow an unauthenticated attacker to access specific files within the web application root directory in affected versions.
CISA due Oct 18, 2026
- Atlassian Multiple Products
- Critical
- CVSS 9.3
- EPSS 12.71%
- Fixed version listed
What to do
Fixed version listed
- Required action
- Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable.
- CISA deadline for US federal agencies
- Oct 18, 2026
Affected products
| Product | Affected | Fixed in |
|---|---|---|
| Atlassian Bamboo Data Center | All other versions | Patch version 10.2.24 and later, Patch version 12.1.12 and later |
| Atlassian Bitbucket Data Center | All other versions | Patch version 10.2.8 and later, Patch version 10.5.1 and later, Patch version 9.4.26 and later |
| Atlassian Confluence Data Center | All other versions | Patch version 10.2.19 and later, Patch version 9.2.26 and later |
| Atlassian Crowd Data Center | All other versions | Patch version 7.2.4 and later, Patch version 7.1.7 and later, Patch version 7.0.3 and later, Patch version 6.3.7 and later |
| Atlassian Crucible Data Center | All other versions | Patch version 4.9.15 and later |
| Atlassian Fisheye Data Center | All other versions | Patch version 4.9.15 and later |
| Atlassian Jira Service Management Data Center | All other versions | Patch version 11.3.12 and later, Patch version 10.3.26 and later, Patch version 5.12.40 and later |
| Atlassian Jira Software Data Center | All other versions | Patch version 11.3.12 and later, Patch version 10.3.26 and later, Patch version 9.12.40 and later |
Advisories and fixes
- Public exploit github.com
Scores and signals
- Exploitation
- Exploited in the wild
- Severity
- Critical, CVSS 9.3 (v4.0, scored by atlassian)
- EPSS
- 12.71% chance of exploitation in the next 30 days (EPSS from FIRST, as of Oct 23, 2026)
- CISA's SSVC decision points
- Exploitation: active. Automatable: no. Technical impact: total. As of Oct 15, 2026.
- Weakness
- CWE-552: Files or Directories Accessible to External Parties
- Vendor
- Atlassian, Multiple Products
Timeline
- Added to CISA's Known Exploited Vulnerabilities catalog: exploited in the wild. US federal agencies must remediate by 2026-10-18.