GHSA-mgc4-wqv7-4pxm is a critical-severity (CVSS 9.8) vulnerability in github.com/apple/swift-nio. A fix is available for github.com/apple/swift-nio — see the affected versions and patch details below.
SwiftNIO vulnerable to HTTP request smuggling using malformed Transfer-Encoding header
Real-World Exposure
github.com/apple/swift-nio📦github.com/apple/swift-nioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects SwiftURL packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Affected SwiftNIO systems are vulnerable to request smuggling attacks, in which they parse a given HTTP message differently from other network parties, potentially seeing a different number of requests than other servers. This can lead to failures of authentication, routing, and other issues.
This vulnerability can be found in the bundled copy of the Node.JS HTTP parser used in the NIOHTTP1 module.
Workarounds
No workaround is available, users must upgrade.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦SwiftURL | github.com/apple/swift-nio | ≥ 1.0.0&&< 1.14.2 | 1.14.2 |
| 📦SwiftURL | github.com/apple/swift-nio | ≥ 2.0.0&&< 2.13.1 | 2.13.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/apple/swift-nio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/apple/swift-nio to 1.14.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mgc4-wqv7-4pxm 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-mgc4-wqv7-4pxm can be triaged on real exposure rather than presence alone.
Tailored to GHSA-mgc4-wqv7-4pxm. 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-mgc4-wqv7-4pxm in your dependencies?
O3 Security finds GHSA-mgc4-wqv7-4pxm across SwiftURL dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.