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CVE-2026-21589

Critical9.3CISA KEV — exploited in the wild

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.

CVSS
9.3v4.0
EPSS (exploit probability)
12.7%96th pct
CISA KEV
Listed

EPSS trendFIRST daily scores, last 90 days

FIRST EPSS rose from 0.7% on 2026-10-06 to 12.7% on 2026-10-20, ranging 0.7%–12.7% across 12 daily scores.
2026-10-06 → 2026-10-20 · 12 days · 0.7%–12.7%
Daily values
FIRST EPSS daily scores for this CVE
Score dateEPSSPercentile
2026-10-2012.7%96.2%
2026-10-1612.7%96.2%
2026-10-152.8%86.1%
2026-10-142.8%86.1%
2026-10-132.8%86.0%
2026-10-122.8%86.0%
2026-10-111.8%77.6%
2026-10-101.8%77.5%
2026-10-091.8%77.5%
2026-10-081.8%77.5%
2026-10-071.8%77.2%
2026-10-060.7%53.0%

CISA KEV entrycatalogue 2026.10.20

Date added
2026-10-15
Federal due date
2026-10-18
Known ransomware use
Unknown

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.

Verbatim from the CISA KEV catalogue (CISA KEV, fetched 2026-10-21 07:34 UTC). The due date applies to US federal agencies under BOD 22-01.

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

Affected products

  • atlassian bitbucket data center
  • atlassian bitbucket server
  • atlassian confluence data center
  • atlassian crowd
  • atlassian jira data center
  • atlassian jira service desk
  • atlassian jira service management
  • atlassian bamboo
  • atlassian crucible
  • atlassian fisheye

Coverage2 articles

References

Facts sourced from NVD, FIRST EPSS, and CISA KEV. Last synced 2026-10-21 07:34 UTC.

  • CVSS & description: NVD 2.0, fetched 2026-10-21 05:34 UTC
  • EPSS: FIRST EPSS, fetched 2026-10-21 07:34 UTC; score date 2026-10-20
  • KEV: CISA KEV, fetched 2026-10-21 07:34 UTC
CVE-2026-21589 | SecurityTabs