Server-Side Request Forgery (SSRF)

Opis

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Inne nazwy

XSPA

Cross Site Port Attack

SSRF

Server-Side Request Forgery

Skutki

• Confidentiality

  Read Application Data

• Integrity

  Execute Unauthorized Code or Commands

• Access Control

  Bypass Protection Mechanism

  By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.

Przykłady podatności

• CVE-2026-33626 SSRF in LLM toolkit accesses arbitrary URLs for images, as exploited in the wild in April 2026 to conduct port scanning [REF-1519]
• CVE-2024-3095 SSRF in LLM application development framework because the URL retriever allows connections to local addresses using a crafted Location header
• CVE-2023-32786 Chain: LLM integration framework has prompt injection (CWE-1427) that allows an attacker to force the service to retrieve data from an arbitrary URL, essentially providing SSRF (CWE-918) and potentially injecting content into downstream tasks.
• CVE-2021-26855 Server Side Request Forgery (SSRF) in mail server, as exploited in the wild per CISA KEV.
• CVE-2021-21973 Server Side Request Forgery in cloud platform, as exploited in the wild per CISA KEV.
• CVE-2016-4029 Chain: incorrect validation of intended decimal-based IP address format (CWE-1286) enables parsing of octal or hexadecimal formats (CWE-1389), allowing bypass of an SSRF protection mechanism (CWE-918).
• CVE-2002-1484 Web server allows attackers to request a URL from another server, including other ports, which allows proxied scanning.
• CVE-2004-2061 CGI script accepts and retrieves incoming URLs.
• CVE-2010-1637 Web-based mail program allows internal network scanning using a modified POP3 port number.
• CVE-2009-0037 URL-downloading library automatically follows redirects to file:// and scp:// URLs

Słabość nadrzędna

• CWE-441 Unintended Proxy or Intermediary ('Confused Deputy')
• CWE-610 Externally Controlled Reference to a Resource in Another Sphere

Kiedy powstaje

• Architecture and Design
• Implementation

Dotyczy

Not Language-Specific, Web Based, AI/ML, Web Server

Uwagi

CWE-918 (SSRF) and CWE-611 (XXE) are closely related, because they both involve web-related technologies and can launch outbound requests to unexpected destinations. However, XXE can be performed client-side, or in other contexts in which the software is not acting directly as a server, so the "Server" portion of the SSRF acronym does not necessarily apply.

Źródła

1. SSRF vs. Business-critical applications: XXE tunneling in SAP — Alexander Polyakov, Dmitry Chastukhin, 2012
2. SSRF vs. Business-critical Applications. Part 1: XXE Tunnelling in SAP NetWeaver — Alexander Polyakov, Dmitry Chastukhin, Alexey Tyurin
3. Cross Site Port Attacks - XSPA - Part 1 — Riyaz Ahemed Walikar, 2012
4. Cross Site Port Attacks - XSPA - Part 2 — Riyaz Ahemed Walikar, 2012
5. Cross Site Port Attacks - XSPA - Part 3 — Riyaz Ahemed Walikar, 2012
6. SSRF attacks and sockets: smorgasbord of vulnerabilities — Vladimir Vorontsov, Alexander Golovko
7. SSRF bible. Cheatsheet — ONsec Lab, 2013
8. Web Portals: Gateway To Information, Or A Hole In Our Perimeter Defenses — Deral Heiland, 2008
9. Server-Side Request Forgery Prevention Cheat Sheet — OWASP, 2019
10. CVE-2026-33626: How attackers exploited LMDeploy LLM Inference Engines in 12 hours — Sysdig Threat Research Team, 2026