How severe is GHSA-83pc-3rw9-qpwj?

GHSA-83pc-3rw9-qpwj has a CVSS score of 5.2/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-83pc-3rw9-qpwj?

GHSA-83pc-3rw9-qpwj affects the following packages: deno (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-83pc-3rw9-qpwj?

Update deno to 2.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-83pc-3rw9-qpwj is resolved across your whole dependency graph.

How do I detect GHSA-83pc-3rw9-qpwj in my crates.io dependencies?

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.

How do I mitigate GHSA-83pc-3rw9-qpwj if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-83pc-3rw9-qpwj?

O3 pinpoints whether GHSA-83pc-3rw9-qpwj is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-83pc-3rw9-qpwj actively exploited in the wild?

No public exploit code has been indexed for GHSA-83pc-3rw9-qpwj yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is GHSA-83pc-3rw9-qpwj?

GHSA-83pc-3rw9-qpwj is classified as Server-Side Request Forgery (SSRF) (CWE-918). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-83pc-3rw9-qpwj published, and has it been updated?

GHSA-83pc-3rw9-qpwj was published on June 16, 2026 and was last updated on July 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀 crates.io

GHSA-83pc-3rw9-qpwj

MEDIUM

GHSA-83pc-3rw9-qpwj is a medium-severity (CVSS 5.2) Server-Side Request Forgery (SSRF) vulnerability in deno. O3 Security confirms whether GHSA-83pc-3rw9-qpwj is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Deno: WebSocket API sandbox bypass via missing post-DNS check

Also known asCVE-2026-49860

Published

Jun 16, 2026

Updated

Jul 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

🦀deno

Real-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 a WebSocket connection was opened, 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 connect to 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.

Deno.connect and fetch() were not affected by this specific issue (a companion advisory covers fetch()).

Who is affected

Users who:

run untrusted or third-party code with deno run, and
rely on --deny-net to 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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`deno`	all versions	2.8.1

Detection & mitigation playbook

Open-source dependency

Detect
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-83pc-3rw9-qpwj 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-83pc-3rw9-qpwj 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-83pc-3rw9-qpwj. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary When a WebSocket connection was opened, 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 connect to 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 circumve

O3 Security · Impact-Aware SCA

Is GHSA-83pc-3rw9-qpwj in your dependencies?

O3 detects GHSA-83pc-3rw9-qpwj 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.

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