CVE-2023-44386 is a medium-severity (CVSS 5.3) CWE-231 vulnerability in github.com/vapor/vapor. A fix is available for github.com/vapor/vapor — see the affected versions and patch details below.
Incorrect request error handling triggers server crash in Vapor
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-44386.
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.
How urgent is this, really
CVE-2023-44386 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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 incorrectly handles errors encountered during parsing of HTTP 1.x requests, triggering a precondition failure in swift-nio due to API misuse and causing immediate termination of the server process.
Impact
This is a denial of service vulnerability, impacting all users of affected versions of Vapor. Because the crash is an explicit assertion failure, there is no corruption of process state and no risk of data leakage or unauthorized code execution. Total impact is limited to an immediately recoverable service interruption.
Patches
The issue is fixed as of Vapor release 4.84.2.
Workarounds
None known at this time.
For more information
If you have any questions or comments about this advisory:
- Open an issue in the Vapor repo
- Ask in Vapor Discord
Acknowledgements
Full credit for reporting this issue goes to @t0rchwo0d, with additional thanks for responsibly disclosing.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦SwiftURL | github.com/vapor/vapor | ≥ 4.83.2&&< 4.84.2 | 4.84.2 |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/vapor/vapor to 4.84.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-44386 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 CVE-2023-44386 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-44386. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-44386 in your dependencies?
O3 Security finds CVE-2023-44386 across SwiftURL dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.