Cyber Resilience

CVE-2026-53421

Apache Syncope 3.0.0 – 3.0.16

Published
20 July 2026
Modified
27 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0068 49th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-53421 is a critical-severity Improper Isolation or Compartmentalization (CWE-653) vulnerability in Apache Syncope. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 49th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SC-39 (Process Isolation) and AC-6 (Least Privilege) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A06:2025 Insecure Design

EU & UK References

Vulnerability Data

Improper Isolation or Compartmentalization vulnerability in Apache Syncope. An administrator with adequate entitlements can achieve remote code execution through the connector subsystem by relying on scripted connectors' (REST and SQL) capability to run Groovy scripts. This issue affects Apache Syncope:…

more

from 3.0.0-M0 through 3.0.16, from 4.0.0-M0 Through 4.0.6, from 4.1.0-M0 through 4.1.1. Users are recommended to upgrade to version 4.0.7 / 4.1.2, which fix this issue by hardening the Groovy security sandbox.

CWE(s)
CWE-653

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
Why these techniques?

RCE via unsandboxed Groovy script execution in Syncope connectors directly enables exploitation of a public-facing app (T1190) and arbitrary command/script execution (T1059).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-42782Same product: Apache Syncope
CVE-2026-63071Same product: Apache Syncope
CVE-2026-53405Same product: Apache Syncope
CVE-2025-57738Same product: Apache Syncope
CVE-2026-62418Same product: Apache Syncope
CVE-2026-57308Same product: Apache Syncope
CVE-2026-23794Same product: Apache Syncope
CVE-2024-45031Same product: Apache Syncope
CVE-2026-42797Same product: Apache Syncope
CVE-2024-38503Same product: Apache Syncope

Affected Assets

apache
syncope
3.0.0 — 3.0.16 · 4.0.0 — 4.0.7 · 4.1.0 — 4.1.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SC-39 Process Isolation
  • CM-7 Least Functionality
  • AC-6 Least Privilege
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 8 hardening rules · 7 OS baselines
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

SC-39 Process Isolation good match
prevent

Directly enforces process isolation to contain Groovy script execution within scripted connectors and block escape to RCE.

CM-7 Least Functionality partial match
prevent

Restricts scripting functionality and disables unnecessary Groovy interpreter capabilities in the connector subsystem.

AC-6 Least Privilege partial match
prevent

Limits connector configuration privileges to the minimum needed, reducing the set of administrators who can supply malicious scripts.

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 full match
prevents

Least-privilege policy directly enforces separation of privilege levels and access rights.

PR.IR-01 mostly match
prevents

Network and environment segmentation implements the isolation required to prevent unauthorized cross-compartment 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.5.3 Segregation of duties mostly match
degrades

Segregation of duties directly enforces separation of privilege levels and functions.

A.8.22 Segregation of networks mostly match
prevents

Network segregation is a classic technical control for isolating different privilege domains.

A.8.27 Secure system architecture and engineering principles mostly match
prevents

Secure system architecture principles explicitly call for isolation and least-privilege boundaries.

A.8.31 Separation of development, test and production environments mostly match
prevents

Separation of development, test and production environments is a direct application of compartmentalization.

A.5.15 Access control partial match
degrades

Access control policies establish the boundaries that isolation must enforce.

A.5.18 Access rights partial match
degrades

Managing access rights is the operational mechanism for compartmentalizing privileges.

References