CVE-2020-1757 — undertow-core
HIGHCVE-2020-1757 is a high-severity (CVSS 8.1) Improper Input Validation vulnerability in io.undertow:undertow-core. A fix is available for io.undertow:undertow-core — see the affected versions and patch details below.
Improper Input Validation in Undertow
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-2020-1757 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 376,715 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-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
A flaw was found in all undertow-2.x.x SP1 versions prior to undertow-2.0.30.SP1, all undertow-1.x.x and undertow-2.x.x versions prior to undertow-2.1.0.Final, where the Servlet container causes servletPath to normalize incorrectly by truncating the path after semicolon which may lead to an application mapping resulting in the security bypass.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | io.undertow:undertow-core | all versions | 2.1.0io.undertow:undertow-core:2.1.0 |
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 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-1757 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-2020-1757 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-1757. 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 Data Grid 7.3.7 | undertow | RHSA-2020:3779 |
| Red Hat Fuse 7.7.0 | undertow | RHSA-2020:3192 |
| Red Hat JBoss EAP 7 | undertow-core | RHSA-2020:2515 |
| Red Hat JBoss EAP 7.2 | undertow-core | RHSA-2020:2061 |
| Red Hat JBoss Enterprise Application Platform 7.1 EUS for RHEL 7 | eap7-undertow-0:1.4.18-12.SP12_redhat_00001.1.ep7.el7 | RHSA-2024:5856 |
| Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 6 | eap7-activemq-artemis-0:2.9.0-4.redhat_00010.1.el6eap | RHSA-2020:2058 |
| Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 7 | eap7-activemq-artemis-0:2.9.0-4.redhat_00010.1.el7eap | RHSA-2020:2059 |
| Red Hat JBoss Enterprise Application Platform 7.2 for RHEL 8 | eap7-activemq-artemis-0:2.9.0-4.redhat_00010.1.el8eap | RHSA-2020:2060 |
Frequently Asked Questions
Is CVE-2020-1757 in your dependencies?
O3 Security finds CVE-2020-1757 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.