GHSA-qvxg-wjxc-r4gg
HIGHVapor vulnerable to denial of service in URLEncodedFormDecoder
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
github.com/vapor/vaporReal-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
Vapor is an HTTP web framework for Swift. Vapor versions earlier than 4.61.1 are vulnerable to a denial of service in the URLEncodedFormDecoder.
Impact
When using automatic content decoding, e.g.
app.post("foo") { request -> String in
let foo = try request.content.decode(Foo.self)
return "\(foo)"
}
An attacker can craft a request body that can make the server crash with the following request:
curl -d "array[_0][0][array][_0][0][array]$(for f in $(seq 1100); do echo -n '[_0][0][array]'; done)[string][_0]=hello%20world" http://localhost:8080/foo
The issue is unbounded, attacker controlled stack growth which will at some point lead to a stack overflow.
Patches
Fixed in 4.61.1
Workarounds
If you don't need to decode Form URL Encoded data, you can disable the ContentConfiguration so it won't be used. E.g. in configure.swift
var contentConfig = ContentConfiguration()
contentConfig.use(encoder: JSONEncoder.custom(dates: .iso8601), for: .json)
contentConfig.use(decoder: JSONDecoder.custom(dates: .iso8601), for: .json)
contentConfig.use(encoder: JSONEncoder.custom(dates: .iso8601), for: .jsonAPI)
contentConfig.use(decoder: JSONDecoder.custom(dates: .iso8601), for: .jsonAPI)
ContentConfiguration.global = contentConfig
For more information
If you have any questions or comments about this advisory:
- Open an issue in the Vapor repo
- Ask in Vapor Discord
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦SwiftURL | github.com/vapor/vapor | all versions | 4.61.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/vapor/vapor. 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 github.com/vapor/vapor to 4.61.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qvxg-wjxc-r4gg 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-qvxg-wjxc-r4gg 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-qvxg-wjxc-r4gg. 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-qvxg-wjxc-r4gg in your dependencies?
O3 detects GHSA-qvxg-wjxc-r4gg across SwiftURL dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.