GHSA-f3h7-gpjj-wcvh
CRITICALSpin applications with specific configuration vulnerable to potential network sandbox escape
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
spin-sdkReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Some specifically configured Spin applications that use self requests without a specified URL authority can be induced to make requests to arbitrary hosts via the Host HTTP header.
If an application's manifest contains a component with configuration such as
allowed_outbound_hosts = ["http://self", "https://self"]
and code such as
let res: Response = spin_sdk::http::send(
Request::new(Method::Get, "/") // Note: the request URI does not contain a URL authority
).await?;
Then that application can be induced to send an outgoing request to another host (leading the app to process the response assuming it comes from another component in the same application). This can be induced with a request such as
curl -H"Host: google.com:80" localhost:3000 # Assuming the application is served on localhost:3000
Note: If using a SDK that does not use
wasi:http/outgoing-handler, the port can be omitted from the URL.
Vulnerable Configurations
The following conditions need to be met for an application to be vulnerable:
- The environment Spin is deployed in routes requests to the Spin runtime based on the request URL instead of the
Hostheader, and leaves theHostheader set to the original value by the client. - The Spin application's component handling the incoming request is configured with an
allowed_outbound_hostslist containing"self". - In reaction to an incoming request, the component makes an outbound request whose URL doesn't include the hostname/port.
If all of these conditions apply, then Spin will use the inbound request's Host header to determine the authority part of the URL if none is explicitly provided in the request's URL.
Setups known not to be vulnerable
Fermyon's Fermyon Cloud serverless product and applications hosted on it are known not to be vulnerable.
Patches
Has the problem been patched? What versions should users upgrade to? Spin version 2.4.3 is being released with this advisory going public.
Workarounds
For deployments of Spin, a workaround is to ensure that the Host header is sanitized to match the application a request is routed to.
For individual applications, multiple workarounds exist:
- Ensure that outgoing requests always sanitize the
Hostheader - Ensure that outgoing requests always provide the hostname in the URL and use that hostname in the
allowed_outbound_hostslist instead ofself - When using Spin 2.4, use application-internal service chaining for intra-application requests
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | spin-sdk | all versions | 2.4.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for spin-sdk. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update spin-sdk to 2.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f3h7-gpjj-wcvh is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-f3h7-gpjj-wcvh is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-f3h7-gpjj-wcvh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-f3h7-gpjj-wcvh in your dependencies?
O3 detects GHSA-f3h7-gpjj-wcvh across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.