CVE-2026-34715 is a medium-severity (CVSS 5.3) CWE-113 vulnerability in ewe. O3 Security confirms whether CVE-2026-34715 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
ewe Has Improper Neutralization of CRLF Sequences in HTTP Headers (HTTP Request/Response Splitting)
Real-World Exposure
eweReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
ewe is a Gleam web server. Prior to version 3.0.6, the encode_headers function in src/ewe/internal/encoder.gleam directly interpolates response header keys and values into raw HTTP bytes without validating or stripping CRLF (\r\n) sequences. An application that passes user-controlled data into response headers (e.g., setting a Location redirect header from a request parameter) allows an attacker to inject arbitrary HTTP response content, leading to response splitting, cache poisoning, and possible cross-site scripting. Notably, ewe does validate CRLF in incoming request headers via validate_field_value() in the HTTP/1.1 parser — but provides no equivalent protection for outgoing response headers in the encoder. This issue has been patched in version 3.0.6.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | ewe | all versions | 3.0.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ewe. 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 ewe to 3.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34715 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-2026-34715 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-2026-34715. 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-2026-34715 in your dependencies?
O3 detects CVE-2026-34715 across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.