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Critical Atlassian Flaw Lets Unauthenticated Attackers Read Known Files Across 8 Products

The Hacker News
· October 6, 2026

AI summary

A critical vulnerability has been discovered in 8 Atlassian Data Center products, allowing unauthenticated attackers to read specific files in the web application root directory. The attacker must have prior knowledge of the file's exact name and path to exploit the flaw. Atlassian has disclosed the issue, assigning it a severity rating of 9.3 out of 10. The vulnerability affects products that are hosted by customers themselves, rather than cloud-based versions. Atlassian disclosed the flaw on October 5 and assigned it the identifier CVE-2026-21589. The flaw does not permit attackers to list the directory's contents, only to read files whose names and paths are already known.

Vulnerabilities mentioned

CVE-2026-21589
UNKNOWN

h3. 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 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.   h3. Context This vulnerability allows an unauthenticated remote attacker to access specific files within the web application root directory in affected versions. h3. Details: * 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, 7.1.1, 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.

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