{"id":"CVE-2026-56676","revision":null,"records":[{"revision":"18f8969e7efd4b7ca7952e8daa75887a","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-56676","aliases":[],"title":"9router: Image prefetch DNS rebinding allows SSRF to internal services","description":"9Router is an AI router & token saver. Prior to 0.5.2, 9router validates image URLs by resolving the host before fetching, but open-sse/translator/concerns/image.js performs the later server-side image fetch with a separate DNS resolution. An authenticated attacker with access to the LLM proxy can use a vision-capable model and an attacker-controlled DNS name that first resolves to a public IP and then rebinds to an internal address, allowing server-side requests to internal-only HTTP services. This issue is fixed in version 0.5.2.","state":0,"publishedAt":"2026-07-10T15:30:49.514+00:00","modifiedAt":"2026-07-13T18:11:54.297+00:00","affected":[{"ecosystem":"Vendor product","name":"9router","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"decolua\",\n                    \"product\": \"9router\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 0.5.2\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L","score":7.4,"severity":"HIGH"}],"references":["https://github.com/decolua/9router/security/advisories/GHSA-cmhj-wh2f-9cgx","https://github.com/decolua/9router/commit/c7d07448c58bec1200741de0b73305b860416b82","https://github.com/decolua/9router/releases/tag/v0.5.2"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-56676","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-56676","identifiers":["CVE-2026-56676"]},"retained":false,"historicalAffected":[]},{"revision":"c35fb5c58bf74864ba8e96f1515d1025","observedAt":"2026-11-07T12:36:31.772+00:00","statement":{"source":"euvd","id":"EUVD-2026-42929","aliases":["CVE-2026-56676","GHSA-cmhj-wh2f-9cgx"],"title":"9Router is an AI router & token saver. Prior to 0.5.2, 9router validates image URLs by resolving the host before fetching, but open-sse/translator/concerns/image.js performs the later server-side image fetch with a separate DNS resolution. …","description":"9Router is an AI router & token saver. Prior to 0.5.2, 9router validates image URLs by resolving the host before fetching, but open-sse/translator/concerns/image.js performs the later server-side image fetch with a separate DNS resolution. An authenticated attacker with access to the LLM proxy can use a vision-capable model and an attacker-controlled DNS name that first resolves to a public IP and then rebinds to an internal address, allowing server-side requests to internal-only HTTP services. This issue is fixed in version 0.5.2.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L","score":7.4,"severity":null}],"references":["https://github.com/decolua/9router/security/advisories/GHSA-cmhj-wh2f-9cgx","https://github.com/decolua/9router/commit/c7d07448c58bec1200741de0b73305b860416b82","https://github.com/decolua/9router/releases/tag/v0.5.2"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-42929","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Jul 10, 2026, 3:30:49 PM","dateUpdated":"Jul 13, 2026, 6:11:54 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-42929","identifiers":["EUVD-2026-42929","CVE-2026-56676","GHSA-cmhj-wh2f-9cgx"]},"retained":false,"historicalAffected":[]},{"revision":"5cd6e29c65794cd4a1c6a53ec8c162a3","observedAt":"2026-10-27T15:15:18.401+00:00","statement":{"source":"nvd","id":"CVE-2026-56676","aliases":[],"title":"9Router is an AI router & token saver. Prior to 0.5.2, 9router validates image URLs by resolving the host before fetching, but open-sse/translator/concerns/image.js performs the later server-side image fetch with a separate DNS resolution. …","description":"9Router is an AI router & token saver. Prior to 0.5.2, 9router validates image URLs by resolving the host before fetching, but open-sse/translator/concerns/image.js performs the later server-side image fetch with a separate DNS resolution. An authenticated attacker with access to the LLM proxy can use a vision-capable model and an attacker-controlled DNS name that first resolves to a public IP and then rebinds to an internal address, allowing server-side requests to internal-only HTTP services. This issue is fixed in version 0.5.2.","state":0,"publishedAt":"2026-07-10T16:16:34.923+00:00","modifiedAt":"2026-10-25T15:10:00.147+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L","score":7.4,"severity":"HIGH"}],"references":["https://github.com/decolua/9router/commit/c7d07448c58bec1200741de0b73305b860416b82","https://github.com/decolua/9router/releases/tag/v0.5.2","https://github.com/decolua/9router/security/advisories/GHSA-cmhj-wh2f-9cgx"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-56676","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-367","CWE-918"],"productCriteria":[],"sourceDates":{"published":"2026-07-10T16:16:34.923","lastModified":"2026-10-25T15:10:00.147"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-56676","identifiers":["CVE-2026-56676"]},"retained":false,"historicalAffected":[]},{"revision":"ecb5d323decb44babd1f40ef1598ed23","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-cmhj-wh2f-9cgx","aliases":["CVE-2026-56676"],"title":"9router: Image prefetch DNS rebinding allows SSRF to internal services","description":"## Summary\n\n9router validates image URLs by resolving the host before fetching, but the later\nserver-side fetch performs a separate DNS resolution. An attacker-controlled DNS name can\nresolve to a public IP during validation and then rebind to an internal Docker/private IP\nduring the fetch. This allows the server-side image prefetch to reach internal-only HTTP\nservices (SSRF).\n\n## Details\n\n- **Affected version / commit:** 9router `v0.4.80` @ `b282f05`.\n- **Reachable through** `/v1/chat/completions` with a **vision-capable model** and an\n  `image_url` content part. A vision-capable model name is required so the image survives\n  modality stripping and the server-side prefetch is armed.\n- The provider used in this reproduction is the bundled **mock provider** — **no real API\n  key and no real provider call**.\n- **internal-admin** (the SSRF target) is **not exposed to the host network**; it is\n  reachable only from inside the Docker network.\n- **rebind-dns** behaviour for `rebind.9r.test`:\n  - first A response → `1.1.1.1` (public) to pass the public-host guard,\n  - second A response → `172.29.0.10` (internal-admin) during the fetch.\n- **internal-admin** logs `GET /ssrf-marker` with `peer=172.29.0.30` (the `proxied-router`\n  container), proving the server-side fetch landed on the internal service.\n- **mock-provider** receives `POST /api/chat` and the flow completes with `HTTP 200`.\n- **Root cause:** DNS TOCTOU — the IP is **not pinned** between the validation resolution\n  (the public-host guard) and the fetch resolution. The guard and the fetch each resolve the\n  hostname independently, so a TTL-0 rebinding authority can return a public IP to the guard\n  and an internal IP to the fetch.\n\n## Proof of Concept\n\nThis repository is a self-contained Docker Compose reproduction. No real provider is called\nand no real API key is required.\n\n1. Build and start the stack:\n   ```bash\n   docker compose up --build\n   ```\n2. Confirm `internal-admin` is unreachable from the host:\n   ```bash\n   curl -i http://127.0.0.1:18083/ssrf-marker   # connection refused / fail\n   docker compose ps                            # internal-admin has NO host port mapping\n   ```\n3. Send the request named **`POST image-prefetch DNS rebinding trigger`** from\n   [`requests.http`](./requests.http), or with curl:\n   ```bash\n   curl -i -X POST http://127.0.0.1:18082/v1/chat/completions \\\n     -H \"Content-Type: application/json\" \\\n     -d '{\n       \"model\": \"ollama-local/gemma3\",\n       \"messages\": [{\"role\":\"user\",\"content\":[\n         {\"type\":\"text\",\"text\":\"reproduction image-prefetch trigger\"},\n         {\"type\":\"image_url\",\"image_url\":{\"url\":\"http://rebind.9r.test:8080/ssrf-marker?case=rebind-trigger\"}}\n       ]}],\n       \"stream\": false\n     }'\n   ```\n\n## Impact\n\n- SSRF to internal HTTP services reachable from the 9router host/container.\n- Depending on the environment, this can reach cloud metadata endpoints, internal admin\n  panels, or be used for internal service discovery.\n- Blind / semi-blind SSRF when the fetched response is not returned to the attacker; an\n  exfil variant (pointing the image at an internal endpoint that returns valid image bytes)\n  can return internal content base64-encoded to the upstream.\n- Requires a code path that prefetches/normalizes remote images for vision-capable\n  providers.\n- No real credential is needed for the reproduction.\n\n## Suggested Fix\n\n- **Pin the resolved IP** after validation and connect to **that** IP (resolve once, then\n  reuse the address for the fetch).\n- Block private, loopback, link-local, multicast, and cloud-metadata ranges **at connect\n  time**, not only at validation time.\n- Perform DNS resolution and IP checks immediately before the request and against the\n  address actually used to connect.\n- Disable redirects, or re-validate every redirect target with the same checks.\n- Enforce an allowlist for image-fetch domains where feasible.\n- Add a timeout, a response size limit, and a content-type check.","state":0,"publishedAt":"2026-09-23T18:12:28+00:00","modifiedAt":"2026-09-23T18:27:56.2189336+00:00","affected":[{"ecosystem":"npm","name":"9router","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"0.5.2"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/decolua/9router/security/advisories/GHSA-cmhj-wh2f-9cgx","https://nvd.nist.gov/vuln/detail/CVE-2026-56676","https://github.com/decolua/9router/commit/c7d07448c58bec1200741de0b73305b860416b82","https://github.com/decolua/9router","https://github.com/decolua/9router/releases/tag/v0.5.2"],"sourceUrl":"https://github.com/advisories/GHSA-cmhj-wh2f-9cgx","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-cmhj-wh2f-9cgx","identifiers":["GHSA-cmhj-wh2f-9cgx","CVE-2026-56676"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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