// CVE

CVE-2026-21589

Critical 9.3 Exploited (KEV)

Atlassian Bamboo Data Center

9.3CVSS
100%EPSS
YesCISA KEV

Summary

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…

Published: 2026-10-05 · In KEV since: 2026-10-15

Analysis

🔴 Critical — actively exploited

How it's exploited: Exploitable over the network (internet-reachable), unauthenticated, no user interaction, and with low complexity.

⚠️ Critical combo: remote, unauthenticated and no interaction → trivial to automate.

Impact: Confidentiality high · Integrity none · Availability none.

Status: Active exploitation confirmed by CISA (KEV).

How to defend:
  • Patch now: it is in CISA's actively-exploited catalog (KEV), with a deadline.
  • Reduce exposure: keep it off the internet; firewall, VPN or network segmentation.
  • Detect: turn this CVE into detection rules.

CVSS 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

The vector encodes how it's exploited (translated above, in the analysis). Break it down in the CVSS tool →

🔗 NVD record CISA KEV 🌉 CVE → detection 🎯 Am I exposed? ⚖️ Prioritize patch

← Back to the Threat Radar

Sources: CISA KEV · EPSS · FIRST.org · NVD. Analysis derived from the CVSS vector and exploitation status (no AI). Informational; always verify against the vendor's official advisory.