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CVE-2026-21589: Atlassian Multiple Products Files or Directories Accessible to External Parties Vulnerability

In short

Atlassian Multiple Products has a weakness classified as files or directories accessible to external parties (CWE-552). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-10-15. NVD lists CVSS 4.0 at 9.3 CRITICAL.

What it is

“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 KEV, retrieved 2026-11-01
“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, 11.3.12 -- Jira Service Management Data Center, introduced in version >= 3.1.0, fix versions 5.12.40, 10.3.26, 11.3.12 -- Bamboo Data Center >= 7.0.1, fix versions 10.2.24, 12.1.12 -- Crucible, fix versions 4.9.15 -- Fisheye, fix version 4.9.15 -- Exploitation requires prior knowledge of the target file's exact name and path. The vulnerability does not include the capability to enumerate or list directory contents.” — NVD, retrieved 2026-11-01

Who is affected

Atlassian Multiple Products. NVD lists the following versions as affected:

  • Atlassian Bitbucket Data Center: from 7.17.0 inclusive, before 9.4.26
  • Atlassian Bitbucket Data Center: from 9.5.0 inclusive, before 10.2.8
  • Atlassian Bitbucket Data Center: from 10.3.0 inclusive, before 10.5.1
  • Atlassian Bitbucket Server: from 4.6.0 inclusive, through 8.14.6
  • Atlassian Confluence Data Center: from 5.10.0 inclusive, before 9.2.26
  • Atlassian Confluence Data Center: from 9.3.0 inclusive, before 10.2.19
  • Atlassian Crowd: from 2.11.0 inclusive, before 6.3.7
  • Atlassian Crowd: from 7.0.0 inclusive, before 7.0.3
  • Atlassian Crowd: from 7.1.0 inclusive, before 7.1.7
  • Atlassian Crowd: from 7.2.0 inclusive, before 7.2.4
  • Atlassian Jira Data Center: from 7.1.0 inclusive, before 9.12.40
  • Atlassian Jira Data Center: from 9.13.0 inclusive, before 10.3.26
  • Atlassian Jira Data Center: from 10.4.0 inclusive, before 11.3.12
  • Atlassian Jira Service Desk: from 3.1.0 inclusive, through 4.13.27
  • Atlassian Jira Service Management: from 4.14.0 inclusive, before 5.12.40
  • Atlassian Jira Service Management: from 5.13.0 inclusive, before 10.3.26
  • Atlassian Jira Service Management: from 10.4.0 inclusive, before 11.3.12
  • Atlassian Bamboo: from 7.0.1 inclusive, before 10.2.24
  • Atlassian Bamboo: from 11.0.0 inclusive, before 12.1.12
  • Atlassian Crucible: before 4.9.15
  • Atlassian Fisheye: before 4.9.15

Exploitation status

CISA KEV added: 2026-10-15. Known ransomware campaign use: Not reported by CISA. Due date CISA set for US federal civilian agencies: 2026-10-18.

Scores

NVD CVSS 4.0: 9.3 CRITICAL; vector 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; source [email protected].

EPSS by FIRST: 99.48%; percentile 99.94; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-552.

Timeline

Source events
DateEvent
2026-10-05T22:16:58.423NVD published
2026-10-15CISA KEV added
2026-10-18CISA KEV due
2026-10-29T13:17:09.847NVD last modified
2026-10-31FIRST EPSS score

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

What to do

  • Confirm whether you run Atlassian Multiple Products and which version.
  • Apply the vendor update or mitigation in the advisory.
  • Follow CISA’s required action.
  • Review the vendor guidance on signs of compromise.
  • Track the fix through completion.

References

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.

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