GHSA-cpgj-f7g3-2pp2
MEDIUMGHSA-cpgj-f7g3-2pp2 is a medium-severity (CVSS 5.2) CWE-693 vulnerability in deno. O3 Security confirms whether GHSA-cpgj-f7g3-2pp2 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Deno: `fetch()` API sandbox bypass via missing DNS resolution check
Blast Radius
denoReal-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
Summary
When fetch() was called, Deno checked the destination hostname against
--deny-net rules but did not re-check the IP addresses that hostname
resolved to. An attacker-controlled script could use a specially crafted domain
name that passes the hostname check yet resolves to a denied IP, bypassing the
network restriction entirely.
Impact
Code running under --deny-net could reach hosts that the user intended to
block. In practice this means network isolation rules — for example, blocking
access to localhost or internal services — could be silently circumvented by
a malicious or compromised dependency.
A companion advisory covers the same class of issue in the WebSocket API.
Who is affected
Users who:
- run untrusted or third-party code with
deno run, and - rely on
--deny-netto restrict which hosts that code can reach.
If you do not use --deny-net, or if you only run fully trusted code, you are
not affected.
Workaround
No workaround is available short of upgrading. If upgrading immediately is not
possible, avoid granting --allow-net to untrusted code that also has
--deny-net restrictions you depend on for security.
Fix
The fetch() DNS resolver now performs a post-resolution check on every IP
address before passing it to the HTTP connector, consistent with how
Deno.connect already behaved.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | deno | all versions | 2.8.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for deno. 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 deno to 2.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cpgj-f7g3-2pp2 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-cpgj-f7g3-2pp2 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-cpgj-f7g3-2pp2. 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-cpgj-f7g3-2pp2 in your dependencies?
O3 detects GHSA-cpgj-f7g3-2pp2 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.