Summary
Vapor's incorrect request error handling triggers server crash
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.
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.
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.
CVE-2023-44386 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.84.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
The issue is fixed as of Vapor release 4.84.2.
Frequently Asked Questions
- What is CVE-2023-44386? CVE-2023-44386 is a medium-severity security vulnerability in github.com/vapor/vapor (swift), affecting versions >= 4.83.2, < 4.84.2. It is fixed in 4.84.2.
- How severe is CVE-2023-44386? CVE-2023-44386 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/vapor/vapor are affected by CVE-2023-44386? github.com/vapor/vapor (swift) versions >= 4.83.2, < 4.84.2 is affected.
- Is there a fix for CVE-2023-44386? Yes. CVE-2023-44386 is fixed in 4.84.2. Upgrade to this version or later.
- Is CVE-2023-44386 exploitable, and should I be worried? Whether CVE-2023-44386 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-44386 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-44386? Upgrade
github.com/vapor/vaporto 4.84.2 or later.