CVE-2017-7559
MEDIUMCVE-2017-7559 is a medium-severity (CVSS 6.1) CWE-444 vulnerability in io.undertow:undertow-core. O3 Security confirms whether CVE-2017-7559 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Undertow vulnerable to Request Smuggling
Blast Radius
io.undertow:undertow-core☕io.undertow:undertow-core☕io.undertow:undertow-coreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
In Undertow 2.x before 2.0.0.Alpha2, 1.4.x before 1.4.17.Final, and 1.3.x before 1.3.31.Final, it was found that the fix for CVE-2017-2666 was incomplete and invalid characters are still allowed in the query string and path parameters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack, or obtain sensitive information from requests other than their own.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.undertow:undertow-core | ≥ 1.4.0&&< 1.4.17.Final | 1.4.17.Final |
| ☕Maven | io.undertow:undertow-core | ≥ 1.3.0&&< 1.3.31.Final | 1.3.31.Final |
| ☕Maven | io.undertow:undertow-core | ≥ 2.0.0.Alpha1&&< 2.0.0.Alpha2 | 2.0.0.Alpha2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.undertow:undertow-core. 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 io.undertow:undertow-core to 1.4.17.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-7559 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-2017-7559 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-2017-7559. 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-2017-7559 in your dependencies?
O3 detects CVE-2017-7559 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.