CVE-2026-62418: Apache Syncope SSRF Vulnerability

CVE-2026-62418 Overview

CVE-2026-62418 is a Server-Side Request Forgery (SSRF) vulnerability [CWE-918] in Apache Syncope. The flaw resides in the Connectors and Resources check functionality. An authenticated attacker with low privileges can coerce the Syncope server into issuing arbitrary HTTP requests to internal or external systems. This enables reconnaissance of internal networks, interaction with metadata services, and pivoting to services otherwise inaccessible from outside the perimeter.

The issue affects Apache Syncope versions 3.0.0-M0 through 3.0.16, 4.0.0-M0 through 4.0.6, and 4.1.0-M0 through 4.1.1. The Apache Syncope project released fixes in versions 4.0.7 and 4.1.2.

Critical Impact
An authenticated low-privileged attacker can force the Syncope server to send crafted HTTP requests to arbitrary hosts, exposing internal services and sensitive metadata endpoints.

Affected Products

Apache Syncope 3.0.0-M0 through 3.0.16
Apache Syncope 4.0.0-M0 through 4.0.6
Apache Syncope 4.1.0-M0 through 4.1.1

Discovery Timeline

2026-07-20 - CVE-2026-62418 published to NVD
2026-07-21 - Last updated in NVD database

Technical Details for CVE-2026-62418

Vulnerability Analysis

Apache Syncope is an open-source identity management system for provisioning, deprovisioning, and orchestrating identities across connected systems. The Connectors and Resources subsystem allows administrators to define outbound connections to target systems. The check functionality validates connectivity to those endpoints by issuing HTTP requests from the Syncope server.

The vulnerability arises because the check endpoint accepts a user-controlled URL or connection target without adequate validation of scheme, host, or destination. An authenticated user with permissions to test connectors and resources can supply an arbitrary target, causing the server to initiate a request on their behalf. Because the request originates from the trusted Syncope host, it bypasses network segmentation controls that would block the attacker directly.

Root Cause

The root cause is missing or insufficient validation of connection targets before the server dispatches HTTP requests during the resource check operation. Syncope does not restrict destinations to an allowlist of expected identity providers or backing stores. There is no filtering of loopback addresses, link-local ranges, cloud metadata endpoints such as 169.254.169.254, or internal RFC1918 networks.

Attack Vector

An attacker authenticated to Syncope with low privileges submits a crafted resource or connector check request. The request specifies a target URL pointing at an internal service, cloud metadata endpoint, or administrative interface. The Syncope server issues the outbound request and, depending on the response handling, may return response content, headers, or timing information to the attacker.

The vulnerability allows enumeration of internal services, retrieval of cloud instance credentials from IMDS endpoints, and interaction with services that trust requests originating from the Syncope host. See the Apache Mailing List Discussion and the Openwall OSS-Security Update for additional technical context.

Detection Methods for CVE-2026-62418

Indicators of Compromise

Outbound HTTP requests from Syncope hosts to internal RFC1918 addresses that are not documented identity backend systems.
Connections from Syncope to cloud metadata IP addresses such as 169.254.169.254 or fd00:ec2::254.
Repeated resource or connector check operations from a single low-privileged account within a short interval.
Syncope audit log entries showing resource check actions with unusual target URLs or non-standard ports.

Detection Strategies

Review Syncope audit logs for ConnectorCheck and ResourceCheck operations initiated by non-administrative accounts.
Correlate application logs with network flow data to identify outbound requests to unexpected destinations from the Syncope service account.
Alert on any HTTP request from Syncope to metadata service IP ranges or loopback addresses.

Monitoring Recommendations

Enable verbose auditing on Syncope administrative APIs and forward logs to a centralized SIEM.
Instrument egress firewalls to log and alert on Syncope-originated traffic that does not match approved identity backend destinations.
Track privilege assignments granting connector or resource management rights and review changes weekly.

How to Mitigate CVE-2026-62418

Immediate Actions Required

Upgrade Apache Syncope to version 4.0.7 or 4.1.2 immediately.
For deployments on the 3.0.x branch, plan migration to a fixed 4.x release, as no fixed 3.0.x version is listed in the advisory.
Audit user accounts holding permissions to check connectors and resources and revoke unnecessary privileges.
Review historical audit logs for suspicious resource check activity from low-privileged accounts.

Patch Information

The Apache Syncope project addressed CVE-2026-62418 in versions 4.0.7 and 4.1.2. Users on affected 4.0.x releases should upgrade to 4.0.7, and users on 4.1.x should upgrade to 4.1.2. Refer to the Apache Mailing List Discussion for the official announcement.

Workarounds

Restrict outbound network access from Syncope hosts using egress firewall rules that allowlist only required identity backend endpoints.
Block Syncope hosts from reaching cloud metadata endpoints such as 169.254.169.254 using host-level firewall rules or IMDSv2 enforcement on AWS.
Limit connector and resource check permissions to a small number of trusted administrators via Syncope role assignments.
Deploy Syncope in a network segment that cannot reach internal management interfaces or sensitive services.

bash

# Example egress restriction using iptables on the Syncope host
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 -p tcp --dport 1:65535 -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -p tcp -m multiport ! --dports 389,636,3306,5432 -j DROP