CVE-2017-7559 — undertow-core
MEDIUMCVE-2017-7559 is a medium-severity (CVSS 6.1) CWE-444 vulnerability in io.undertow:undertow-core. A fix is available for io.undertow:undertow-core — see the affected versions and patch details below.
Undertow vulnerable to Request Smuggling
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-2017-7559 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 377,333 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
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.Finalio.undertow:undertow-core:1.4.17.Final |
| ☕Maven | io.undertow:undertow-core | ≥ 1.3.0&&< 1.3.31.Final | 1.3.31.Finalio.undertow:undertow-core:1.3.31.Final |
| ☕Maven | io.undertow:undertow-core | ≥ 2.0.0.Alpha1&&< 2.0.0.Alpha2 | 2.0.0.Alpha2io.undertow:undertow-core: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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2017-7559 can be triaged on real exposure rather than presence alone.
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.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat JBoss A-MQ 6.3 | see advisory | RHSA-2018:1322 |
| Red Hat JBoss EAP 7 | see advisory | RHSA-2017:3456 |
| Red Hat JBoss EAP 7 | wildfly-undertow | RHSA-2018:0003 |
| Red Hat JBoss Enterprise Application Platform 7.0 for RHEL 6 | eap7-activemq-artemis-0:1.1.0-19.SP24_redhat_1.1.ep7.el6 | RHSA-2018:0002 |
| Red Hat JBoss Enterprise Application Platform 7.0 for RHEL 6 | eap7-jboss-ec2-eap-0:7.0.9-2.GA_redhat_2.ep7.el6 | RHSA-2018:0005 |
| Red Hat JBoss Enterprise Application Platform 7.0 for RHEL 7 | eap7-activemq-artemis-0:1.1.0-19.SP24_redhat_1.1.ep7.el7 | RHSA-2018:0004 |
| Red Hat JBoss Enterprise Application Platform 7.1 for RHEL 6 | eap7-activemq-artemis-0:1.5.5.008-1.redhat_1.1.ep7.el6 | RHSA-2017:3454 |
| Red Hat JBoss Enterprise Application Platform 7.1 for RHEL 6 | eap7-jboss-ec2-eap-0:7.1.0-5.GA_redhat_5.ep7.el6 | RHSA-2017:3458 |
Frequently Asked Questions
Is CVE-2017-7559 in your dependencies?
O3 Security finds CVE-2017-7559 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.