Horizon Alert
Summary of the vulnerability and why it matters
This advisory concerns a critical vulnerability in Zalando Skipper, an HTTP router and reverse proxy. The issue, a Server-Side Request Forgery, allows unauthorized requests to be made from the affected system, potentially exposing internal resources or leading to other security risks. Given its role as an edge component, exposure is considered likely, making it important to confirm relevance and assess potential impact.
- Critical flaw in proxy software.
- Proxy software is likely exposed externally.
- Confirm relevance and exposure of proxy software.
Attack Path
How an attacker could exploit the issue
An attacker could exploit this vulnerability by sending specially crafted requests to an exposed instance of the affected software. This could allow them to trick the software into making unintended requests on their behalf to internal or external resources, potentially leading to the disclosure of sensitive information or the manipulation of other systems.
- Accessible over the network without authentication.
- Triggered by sending specific requests to the software.
- Enables unauthorized access to internal resources.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could allow an attacker to make the Zalando Skipper proxy issue requests to arbitrary internal or external resources. When the proxy is processing specific requests, an attacker could trick it into connecting to a URL of their choosing. This could lead to the proxy accessing sensitive internal network resources or external services.
- Internal network access.
- Attacker-controlled requests.
- Information disclosure or denial of service.
Operational Fix
Recommended remediation, mitigation, and detection steps
This critical SSRF vulnerability in Zalando Skipper, an HTTP router and reverse proxy, likely impacts teams responsible for ingress traffic management and backend service routing. The first practical step is to locate all instances of the affected technology, verify their exposure to external networks, confirm their business criticality, and identify the accountable system owner before planning remediation.
- Ownership: Platform and network security teams.
- Verify first: External reachability and business criticality.
- Action: Coordinate vendor engagement and plan remediation.
