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Known exploited vulnerability · CISA KEV

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.

CVE-2026-21589

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2026-10-15: attackers are using it right now.

CISA KEV
Listed
Added 2026-10-15 · federal fix-by 2026-10-18
EPSS (30 days)
99%
Higher than 99.9% of CVEs · 2026-11-01
CVSS v4.0
9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

What CISA says

Atlassian Multiple Products Files or Directories Accessible to External Parties Vulnerability

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. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

NVD description · published 2026-10-05

This is a vulnerability in Bitbucket Data Center, Confluence Data Center, Jira Service Management Data Center, Jira Software Data Center, Bamboo Data Center. Crowd Data Center, Crucible and Fisheye. This Arbitrary File Access vulnerability allows an unauthenticated attacker to access specific files within the web application root directory in affected versions. Exploitation requires prior knowledge of the target file's exact name and path; this vulnerability does not allow attackers to enumerate or list directory contents. In some configurations, there may be some sensitive files that make this highly severe. This vulnerability allows an unauthenticated remote attacker to access specific files within the web application root directory in affected versions. The vulnerability must be addressed for affected versions of: -- Bitbucket Data Center, introduced in version >= 4.6.0, fix versions: 9.4.26, 10.2.8, 10.5.1 -- Confluence Data Center, introduced in version >= 5.10.0, fix versions 9.2.26, 10.2.19 -- Crowd Data Center, introduced in version >= 2.11.0, fix versions 6.3.7, 7.0.3, 7.1.7, 7.2.4 -- Jira Software Data Center, introduced in version >= 7.1.0, fix versions 9.12.40, 10.3.26,

Full record on NVD

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How to check if you are exposed to CVE-2026-21589

  1. Find every Atlassian Multiple Products system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
  2. Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
  3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2026-21589.

US federal agencies had to fix this by 2026-10-18. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2026-21589. Check the vendor advisory for the exact fixed builds before you sign anything off.

ProductVulnerable versions
Atlassian Bitbucket Data Centerfrom 7.17.0 before 9.4.26; from 9.5.0 before 10.2.8; from 10.3.0 before 10.5.1
Atlassian Bitbucket Serverfrom 4.6.0 up to and including 8.14.6
Atlassian Confluence Data Centerfrom 5.10.0 before 9.2.26; from 9.3.0 before 10.2.19
Atlassian Crowdfrom 2.11.0 before 6.3.7; from 7.0.0 before 7.0.3; from 7.1.0 before 7.1.7; from 7.2.0 before 7.2.4
Atlassian Jira Data Centerfrom 7.1.0 before 9.12.40; from 9.13.0 before 10.3.26; from 10.4.0 before 11.3.12
Atlassian Jira Service Deskfrom 3.1.0 up to and including 4.13.27

NVD lists 4 more affected products; see the full record on NVD.

Timeline

  1. · Published in the National Vulnerability Database
  2. · Added to CISA's Known Exploited Vulnerabilities catalog, 10 days after it was published
  3. · Fix-by date for US federal agencies, passed 14 days ago

Vendor advisories and fixes

Weakness type

More exploited Atlassian vulnerabilities

CISA lists 14 exploited Atlassian vulnerabilities. The closest matches:

Keep going

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

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