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[ CVE-2026-21589 · Published 5 Oct 2026 ]

Unauthenticated file read in Atlassian Data Center products

Exploited · CISA KEV CVSS 7.5 EPSS 13%4 agency advisoriesFix available

[ Why it matters ]Priority signals

  • Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2026-10-15
  • EPSS: 13% chance of exploitation in the next 30 days (higher than 96% of CVEs)
  • Urgent advisory from CERT-EU

[ Analyst view ]Is this a red alert for you?

Red alert

CISA lists it as exploited and it needs no credentials, even though it only allows reading files.

Red alert if
You run any of the listed Atlassian Data Center products, Crucible or Fisheye reachable from the internet.
Can wait if
You only use Atlassian Cloud, or your Data Center servers are reachable only from the internal network and you patch this week.
What it is
An arbitrary file access flaw in Bitbucket, Confluence, Jira Software, Jira Service Management, Bamboo and Crowd Data Center, Crucible and Fisheye lets an attacker read specific files in the web application root without logging in. The attacker must know the exact file name and path.
Impact
An attacker can read files from the server without credentials, but cannot list directories or change anything. Depending on the setup, those files can include configuration with secrets or tokens, which an attacker could use to log in to the product or connected systems.

How an attack would work MITRE ATT&CK

  1. T1190 Exploit Public-Facing ApplicationThe attacker requests known file paths from the internet-facing Atlassian server.
  2. T1552 Unsecured CredentialsThey look for configuration files that hold passwords, keys or tokens.
  3. T1078 Valid AccountsSecrets they find are used to log in to the product or the systems it connects to.

What to do

  1. Upgrade every affected Atlassian Data Center product to the fixed version listed in Atlassian's advisory for CVE-2026-21589.
  2. Until then, keep the products off the open internet or put them behind a VPN or access proxy.
  3. Review web server logs for unusual requests for files in the application directory.
  4. Rotate any secrets stored in files under the web root, such as API tokens and integration passwords.
Written with AI from the sources on this page on 23 Oct 2026. Check the vendor's advisory before you act.

[ Description ]Official description

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.

CISA: 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.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 18 Oct 2026): 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.

[ Advisories ]Government CERT advisories

[ References ]References