Security Resilience

CVE-2026-21589

Atlassian Crowd 2.11.0 – 6.3.7

CISA KEVActive ExploitationEUVD Exploited
Published
05 October 2026
Modified
16 October 2026
KEV Added
15 October 2026
Patch / advisory
View advisory
CVSS Score v4 9.3
Click a component to see what it means
Raw vectorCVSS: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
EPSS Score 0.028 86th percentile
Risk Priority 75 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-21589 is a critical-severity Files or Directories Accessible to External Parties (CWE-552) vulnerability in Atlassian Crowd. Its CVSS base score is 9.3 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Automated Collection (T1119); ranked in the top 14% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-6 (Least Privilege) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-552
KEV Date Added
15 October 2026

Related Threats

MITRE ATT&CK Enterprise Techniques

T1119 Automated Collection Collection
Once established within a system or network, an adversary may use automated techniques for collecting internal data.
attack.mitre.org →
T1552.001 Credentials In Files Credential Access
Adversaries may search local file systems and remote file shares for files containing insecurely stored credentials.
attack.mitre.org →
T1552.004 Private Keys Credential Access
Adversaries may search for private key certificate files on compromised systems for insecurely stored credentials.
attack.mitre.org →
T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
attack.mitre.org →
T1001.001 Junk Data Command And Control
Adversaries may add junk data to protocols used for command and control to make detection more difficult.
attack.mitre.org →
T1001.003 Protocol or Service Impersonation Command And Control
Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-48661Shared CWE-552
CVE-2023-34834Shared CWE-552
CVE-2025-4634Shared CWE-552
CVE-2025-11371Shared CWE-552
CVE-2023-25260Shared CWE-552
CVE-2024-21403Shared CWE-552
CVE-2024-48838Shared CWE-552
CVE-2025-14896Shared CWE-552
CVE-2026-75464Shared CWE-552
CVE-2026-40631Shared CWE-552

Affected Assets

atlassian
bitbucket data center
7.17.0 — 9.4.26 · 9.5.0 — 10.2.8 · 10.3.0 — 10.5.1
atlassian
bitbucket server
4.6.0 — 8.14.6
atlassian
confluence data center
5.10.0 — 9.2.26 · 9.3.0 — 10.2.19
atlassian
crowd
2.11.0 — 6.3.7 · 7.0.0 — 7.0.3 · 7.1.0 — 7.1.7
atlassian
jira data center
7.1.0 — 9.12.40 · 9.13.0 — 10.3.26 · 10.4.0 — 11.3.12
atlassian
jira service management
3.1.0 — 5.12.40 · 5.13.0 — 10.3.26 · 10.4.0 — 11.3.12
atlassian
bamboo
7.0.1 — 10.2.24 · 11.0.0 — 12.1.12
atlassian
crucible
≤ 4.9.15
atlassian
fisheye
≤ 4.9.15

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 2 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V8.4.2

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement partial match

AC-3 directly enforces authorization checks on access to files and directories, stopping unauthorized external exposure.

AC-6 Least Privilege partial match

AC-6 limits granted privileges, reducing the chance that files or directories become reachable by external parties.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-05 partial match
blocks

Enforcing least-privilege permissions and authorization policies directly prevents unauthorized file/directory exposure.

PR.DS-01 partial match
blocks

Data-at-rest protections such as encryption or ACLs reduce the impact of unintended file exposure.

PR.IR-01 partial match
blocks

Logical segmentation and access protections stop external parties from reaching files that should remain internal.

PR.PS-01 partial match
blocks

Hardened configuration baselines commonly include file-system permission settings that limit external access.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.7.6 Working in secure areas partial match
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248579 OL 8 must restrict access to the kernel message buffer. blocks CWE-552
  • V-248597 There must be no "shosts.equiv" files on the OL 8 operating system. blocks CWE-552

References