Atlassian Jira/Confluence/Bitbucket - Pre-Auth Arbitrary File Read

CVE Details

• Protection status: Protected by Atomicorp rules · About protection statuses
• CVE: CVE-2026-21589
• Name: Atlassian Jira/Confluence/Bitbucket - Pre-Auth Arbitrary File Read
• Severity: Critical
• CVSS: 9.3 (v4.0) (Critical)
• CVSS version: 4.0
• CVSS source: atlassian CNA
• 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/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
  • Attack vector: Network
  • Attack complexity: Low
  • Attack requirements: None
  • Privileges required: None
  • User interaction: None
  • Vulnerable-system confidentiality: High
  • Vulnerable-system integrity: None
  • Vulnerable-system availability: None
  • Subsequent-system confidentiality: High
  • Subsequent-system integrity: High
  • Subsequent-system availability: High
  • Safety: Not defined
• CWE: CWE-552 — Files or Directories Accessible to External Parties
• Related CAPEC attack patterns (via MITRE CWE relationships): CAPEC-150 (opens in a new tab) , CAPEC-639 (opens in a new tab)
• Vendor: atlassian
• Vulnerable products: bitbucket data center , bitbucket server , confluence data center , crowd , jira data center , jira service desk , jira service management , bamboo , crucible , fisheye , jira,confluence,bitbucket
• CVE published: 2026-10-05
• CVE last modified: 2026-10-19
• Affected versions (NVD configurations):
  • bitbucket data center: >= 7.17.0, < 9.4.26
  • bitbucket data center: >= 9.5.0, < 10.2.8
  • bitbucket data center: >= 10.3.0, < 10.5.1
  • bitbucket server: >= 4.6.0, <= 8.14.6
  • confluence data center: >= 5.10.0, < 9.2.26
  • confluence data center: >= 9.3.0, < 10.2.19
  • crowd: >= 2.11.0, < 6.3.7
  • crowd: >= 7.0.0, < 7.0.3
  • crowd: >= 7.1.0, < 7.1.7
  • crowd: >= 7.2.0, < 7.2.4
  • jira data center: >= 7.1.0, < 9.12.40
  • jira data center: >= 9.13.0, < 10.3.26
  • jira data center: >= 10.4.0, < 11.3.12
  • jira service desk: >= 3.1.0, <= 4.13.27
  • jira service management: >= 4.14.0, < 5.12.40
  • jira service management: >= 5.13.0, < 10.3.26
  • jira service management: >= 10.4.0, < 11.3.12
  • bamboo: >= 7.0.1, < 10.2.24
  • bamboo: >= 11.0.0, < 12.1.12
  • crucible: < 4.9.15
  • fisheye: < 4.9.15
• EPSS: 0.1271; 96.3th percentile as of 2026-10-21 (FIRST (opens in a new tab) )
• CISA KEV: Listed (added 2026-10-15)
  • Known ransomware campaign use: Unknown
• Latest Update: 2026-10-07
• Selected Rule IDs observed: 340024
• Matching rules: 1; rules with blocking actions: 1
• Would-block Rule IDs: 340024
• Request surfaces inspected: JSON request data, Request URI, Request arguments, Request headers, SOAP request data

Vulnerability 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.

Recommended Actions

1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (340024 ) have not been locally disabled. Atomicorp commercial rules are enabled by default. If you use Atomic WAF, review the applicable policy and rule settings.

2. Apply the vendor’s remediation. WAF protection is defense in depth and does not replace upgrading or following the affected vendor’s guidance.

   • Affected versions: Atlassian Bamboo Data Center version All other versions.
   • Versions reported unaffected: Atlassian Bamboo Data Center version Patch version 10.2.24 and later.
   • Versions reported unaffected: Atlassian Bamboo Data Center version Patch version 12.1.12 and later.
   • Affected versions: Atlassian Bitbucket Data Center version All other versions.
   • Versions reported unaffected: Atlassian Bitbucket Data Center version Patch version 10.2.8 and later.
   • Versions reported unaffected: Atlassian Bitbucket Data Center version Patch version 10.5.1 and later.
   • Versions reported unaffected: Atlassian Bitbucket Data Center version Patch version 9.4.26 and later.
   • Affected versions: Atlassian Confluence Data Center version All other versions.
   • Versions reported unaffected: Atlassian Confluence Data Center version Patch version 10.2.19 and later.
   • Versions reported unaffected: Atlassian Confluence Data Center version Patch version 9.2.26 and later.
   • Affected versions: Atlassian Crowd Data Center version All other versions.
   • Versions reported unaffected: Atlassian Crowd Data Center version Patch version 7.2.4 and later.
   • Versions reported unaffected: Atlassian Crowd Data Center version Patch version 7.1.7 and later.
   • Versions reported unaffected: Atlassian Crowd Data Center version Patch version 7.0.3 and later.
   • Versions reported unaffected: Atlassian Crowd Data Center version Patch version 6.3.7 and later.
   • Affected versions: Atlassian Crucible Data Center version All other versions.
   • Versions reported unaffected: Atlassian Crucible Data Center version Patch version 4.9.15 and later.
   • Affected versions: Atlassian Fisheye Data Center version All other versions.
   • Versions reported unaffected: Atlassian Fisheye Data Center version Patch version 4.9.15 and later.
   • Affected versions: Atlassian Jira Service Management Data Center version All other versions.
   • Versions reported unaffected: Atlassian Jira Service Management Data Center version Patch version 11.3.12 and later.
   • Versions reported unaffected: Atlassian Jira Service Management Data Center version Patch version 10.3.26 and later.
   • Versions reported unaffected: Atlassian Jira Service Management Data Center version Patch version 5.12.40 and later.
   • Affected versions: Atlassian Jira Software Data Center version All other versions.
   • Versions reported unaffected: Atlassian Jira Software Data Center version Patch version 11.3.12 and later.
   • Versions reported unaffected: Atlassian Jira Software Data Center version Patch version 10.3.26 and later.
   • Versions reported unaffected: Atlassian Jira Software Data Center version Patch version 9.12.40 and later.
   • The CVE record does not include written upgrade or workaround instructions, but it does publish the following patch or mitigation reference:
     • Patch or mitigation information (opens in a new tab)
     • Patch or mitigation information (opens in a new tab)
     • Patch or mitigation information (opens in a new tab)
     • Patch or mitigation information (opens in a new tab)
     • Patch or mitigation information (opens in a new tab)
     • Patch or mitigation information (opens in a new tab)
     • Patch or mitigation information (opens in a new tab)
     • Patch or mitigation information (opens in a new tab)
   • CISA KEV 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 federal remediation due date: 2026-10-18

3. Validate after changes. Confirm rule updates are current, review WAF events for the affected application, and test application behavior after vendor upgrades, mitigations, or local policy changes.

Research Notes

Atomicorp WAF protections are designed around attack techniques and exploit behaviors, allowing existing protections to apply across multiple vulnerabilities without requiring a unique rule for every CVE.

Public Vulnerability References

• NVD (opens in a new tab)
• CVE Record (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/BAM-26567 (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/BSERV-20604 (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/CONFSERVER-104488 (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/CRUC-8741 (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/CWD-6610 (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/FE-7583 (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/JRASERVER-79546 (opens in a new tab)
• Vendor advisory: https://jira.atlassian.com/browse/JSDSERVER-16809 (opens in a new tab)
• Exploit or technical research: https://github.com/watchtowrlabs/watchTowr-vs-Atlassian-CVE-2026-21589 (opens in a new tab)
• CVE authority reference: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21589 (opens in a new tab)

Test or Research Source

• Source: http/cves/2026/CVE-2026-21589.yaml (opens in a new tab)
• Tags: atlassian, bitbucket, confluence, cve, cve2026, jira, lfi, path-traversal

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

• Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
• Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
• Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
• Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
• Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ (opens in a new tab) .