# Server-side request forgery (SSRF)

A server-side fetch crosses the feature’s destination, network, or credential policy.

**Candidate CWE:** [CWE-918](https://cwe.mitre.org/data/definitions/918.html)

## Test hypothesis

Start with an ordinary controlled receiver. In the replica, compare a policy-permitted destination with an owner-designated prohibited canary, and separately test one controlled redirect between them.

## Evidence required

Correlated server/receiver logs show the prohibited request or synthetic authority transfer. State whether evidence proves DNS, HTTP connectivity, readable response, or credential forwarding.

## Rule out false positives

Intended public URL fetching, a callback from your own browser, or DNS resolution without HTTP access does not prove the broader claim.

## Playbook and command references

- [Server-side fetching and network trust boundaries](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/ssrf-boundary.html) — Separate an intended fetch from a request that reaches a prohibited destination, forwards authority, or exposes a protected response.

[Find the associated command snippets](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/commands.html?q=Server-side%20fetching%20and%20network%20trust%20boundaries)

## Referenced by these target playbooks

[Web & API](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/web-api.html) · [OSS & self-hosted](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/oss.html) · [Cloud & containers](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/cloud.html) · [AI, agents & MCP](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/ai.html) · [Desktop & extensions](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/desktop.html)

## Report checklist

- [ ] Capture the affected version, configuration, identities, and object ownership.
- [ ] Preserve a valid baseline and a negative control.
- [ ] Reproduce the forbidden data access, action, or state change on controlled fixtures.
- [ ] Explain the intended security rule and why the observed behavior violates it.
- [ ] State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.

## Conditional ATT&CK mapping

- [T1552.005 · Unsecured Credentials: Cloud Instance Metadata API](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/attack.html#T1552-005) — **Only if:** SSRF or local access reaches cloud instance metadata and demonstrates access to credential-bearing metadata; use isolated fixtures or explicitly permitted controlled identities. **Not established by:** An outbound callback, generic internal reachability, or harmless metadata document alone does not prove credential access. Do not infer a metadata-to-cloud takeover chain.

## Primary references

- [PortSwigger SSRF](https://portswigger.net/web-security/ssrf)

[Back to the complete vulnerability catalog](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/vulnerabilities.html)