CVE-2023-38697 is a medium-severity (CVSS 5.8) CWE-444 vulnerability in protocol-http1. O3 Security confirms whether CVE-2023-38697 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
protocol-http1 HTTP Request/Response Smuggling vulnerability
Real-World Exposure
protocol-http1Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
protocol-http1 provides a low-level implementation of the HTTP/1 protocol. RFC 9112 Section 7.1 defined the format of chunk size, chunk data and chunk extension. The value of Content-Length header should be a string of 0-9 digits, the chunk size should be a string of hex digits and should split from chunk data using CRLF, and the chunk extension shouldn't contain any invisible character. However, Falcon has following behaviors while disobey the corresponding RFCs: accepting Content-Length header values that have + prefix, accepting Content-Length header values that written in hexadecimal with 0x prefix, accepting 0x and + prefixed chunk size, and accepting LF in chunk extension. This behavior can lead to desync when forwarding through multiple HTTP parsers, potentially results in HTTP request smuggling and firewall bypassing. This issue is fixed in protocol-http1 v0.15.1. There are no known workarounds.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | protocol-http1 | all versions | 0.15.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protocol-http1. 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 protocol-http1 to 0.15.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-38697 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 CVE-2023-38697 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 CVE-2023-38697. 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-2023-38697 in your dependencies?
O3 detects CVE-2023-38697 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.