Summary
Open WebUI: Any authenticated user can reach internal services and cloud metadata via NAT64-encoded URLs
Open WebUI fetches user-supplied URLs on the server for RAG URL ingestion, URL-to-markdown conversion and web-search content retrieval, and decides whether a destination is allowed by asking whether its IP address is globally routable. That test operates on the literal IPv6 address and does not look at the IPv4 address embedded inside it. On a deployment whose network has a NAT64 gateway, any verified user can wrap an internal or cloud-metadata IPv4 address in the NAT64 well-known prefix, pass the filter, and receive the internal response body back through the API.
Preconditions
- Any verified (authenticated) user account. No admin role, no elevated permission.
- Default configuration:
ENABLE_LOCAL_WEB_FETCHoff, the defaultWEB_FETCH_FILTER_LISTmetadata blocklist in place. Neither prevents this, because the blocklist matches hostname strings and the NAT64 literal is not one of them. - The deployment's network must provide NAT64 translation for the well-known
64:ff9b::/96prefix, which is the common default on IPv6-only and dual-stack cloud and Kubernetes networks. - Deployments on IPv4-only networks, or on any network without a NAT64 gateway, are not affected: the address has nowhere to route.
Root cause
backend/open_webui/retrieval/web/utils.py,validate_url(), the pre-fetch check on the submitted URL.backend/open_webui/retrieval/web/utils.py,_ssrf_safe_new_conn()and_SSRFSafeResolver, the connect-time re-checks that defeat DNS rebinding.
All three decided reachability from ipaddress.ip_address(ip).is_global applied to the literal address. That predicate answers whether an IPv6 address sits in globally-routable space, which is a different question from where the packet actually ends up once a transition gateway translates it. The NAT64 well-known prefix is by design a global prefix carrying an arbitrary IPv4 destination, so an internal target wrapped in it satisfies the check while reaching exactly what the check exists to prevent. Because the same predicate backed the connect-time re-checks, no later layer caught it either. The fix inspects every standardized transition encoding rather than only the NAT64 prefix, since the same reasoning error applies to each of them.
Proof of concept
Against the real POST /api/v1/retrieval/process/web flow on v0.10.2 as an authenticated user, with internal HTTP services returning a marker string. The plain forms are rejected with HTTP 400:
http://169.254.169.254/latest/meta-data/ -> 400
http://127.0.0.1/ -> 400
http://[::ffff:169.254.169.254]/ -> 400
http://metadata.google.internal/ -> 400
The NAT64 encodings of the same targets are accepted, and the response body is returned in the content field:
http://[64:ff9b::a9fe:a9fe]/latest/meta-data/iam/security-credentials/ -> 200, marker returned
http://[64:ff9b::7f00:1]/admin/internal-status -> 200, marker returned
NAT64 translation was modelled by binding the translated addresses locally rather than by routing through a real NAT64 gateway; everything else, including the request flow and the validation code, is the unmodified v0.10.2 path. After the fix both URLs return 400 while http://[64:ff9b::808:808]/ (8.8.8.8, public) still returns 200, confirming no over-blocking.
Credits
- tonghuaroot, reported the transition-form gap in the address classification and supplied the fix approach.
Impact
On an affected network a low-privilege user can read GET responses from services the server can reach but the internet cannot: cloud instance metadata including IAM role credentials, loopback-bound admin surfaces, and internal APIs in the same VPC or cluster. The response body is returned to the caller, so this is full-read, not blind. Exploitation is not universal, it depends entirely on the deployment's network providing NAT64 translation, which is why the score carries high attack complexity. Deployments without NAT64 lose nothing here.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2026-70485 has a CVSS score of 7.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.11.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed in v0.11.0 by commit 1717b493d. Address classification now unwraps the IPv4 embedded in IPv6 transition encodings before deciding whether a destination is global, and applies that at all three checkpoints. NAT64-wrapped public destinations continue to work. Upgrading to v0.11.0 fully resolves the issue with no configuration change.
Frequently Asked Questions
- What is CVE-2026-70485? CVE-2026-70485 is a high-severity server-side request forgery (SSRF) vulnerability in open-webui (pip), affecting versions >= 0.9.0, < 0.11.0. It is fixed in 0.11.0. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2026-70485? CVE-2026-70485 has a CVSS score of 7.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of open-webui are affected by CVE-2026-70485? open-webui (pip) versions >= 0.9.0, < 0.11.0 is affected.
- Is there a fix for CVE-2026-70485? Yes. CVE-2026-70485 is fixed in 0.11.0. Upgrade to this version or later.
- Is CVE-2026-70485 exploitable, and should I be worried? Whether CVE-2026-70485 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-70485 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-70485? Upgrade
open-webuito 0.11.0 or later.